NEW: The word "God" does not appear in the Democratic platform
NEW: A new poll shows little convention bounce for Mitt Romney
Rep. Ryan keeps up his efforts to link Obama to Jimmy Carter's one-term presidency
Michelle Obama will speak on the convention's first night
CHARLOTTE, North Carolina (CNN) -- Facing a close election and Republican attacks that they have made things worse while in power, Democrats seek to emphasize the tough decisions President Barack Obama has made and additional steps needed to bolster the middle class at their three-day national convention that began Tuesday.
The political conclave that will formally nominate Obama for a second term serves as a response to last week's Republican convention that nominated Mitt Romney as the GOP challenger in November.
Senior campaign officials told CNN on condition of not being identified that the convention has three main objectives -- to outline the clear choice facing voters, to highlight Obama's leadership in championing necessary but politically unpopular steps such as health care reform and the auto industry bailout, and to present a detailed plan for creating jobs for the middle class.
Gaveled to order by Rep. Debbie Wasserman Schultz on Tuesday, the convention's first night speakers include former Ohio Gov. Ted Strickland, Chicago Mayor Rahm Emanuel, San Antonio Mayor Julian Castro and first lady Michelle Obama, who will "tell a personal story about the president as only she can," one of the Obama campaign officials said.
Obama told supporters at a campaign event in Norfolk, Virginia, that viewers would be hearing Tuesday night from "the star" of his family.
"I'm going to be at home, watching it with my girls and I'm going to try not to let them see their daddy cry, because when Michelle starts talking, I get all misty," he said.
Former President Bill Clinton headlines the second night with a speech formally nominating the president, and Obama concludes the convention with his nationally televised acceptance speech on Thursday night.
Democrats have released their party platform that focuses on improving the economic situation for middle-class Americans, and also contains language endorsing same-sex marriage and abortion rights that directly contrasts with the Republican platform adopted last week. In a break from past conventions, the platform does not include the word "God" or label Jerusalem as the capital of Israel -- two more issues that differ from Romney and Republicans.
"It's going to be up to you. You'll make the choice," Obama told the Norfolk State University crowd on Tuesday in framing the election as a decision between starkly different visions for the country's direction.
"We're going to lay out the case for moving the economy forward. President Obama and speakers throughout the week will talk about and have an honest conversation about where we were when he first took office and where we are now after four years of his policies and 29 straight months of job growth in the private sector," Schultz, the chairwoman of the Democratic National Committee, told CNN Tuesday.
Romney's campaign is focused on the question of whether Obama has made life better for Americans, arguing that continued high unemployment and a sluggish economic recovery from the 2008 recession show that White House policies have failed to deliver promised results.
The "are you better off" strategy was famously employed in 1980 by Ronald Reagan, who asked voters that question when running against incumbent Democrat Jimmy Carter at a time of national economic woes. Reagan went on to win, and the Romney campaign has repeatedly invoked his name this year while seeking to link Obama and Carter as failed leaders.
GOP vice presidential candidate Rep. Paul Ryan has led efforts to link Obama with the Carter legacy, telling a campaign stop on Tuesday in Westlake, Ohio, that "when it comes to jobs, President Obama makes the Jimmy Carter years look like the good old days."
"If we fired Jimmy Carter, then why would we rehire Barack Obama now?" Ryan said to cheers.
The Democratic platform points to accomplishments made over the past four years, but argues for a second Obama term by saying more work remains to be done on fixing the economy and making the country more secure. It also pins the blame for rising deficits and debt, as well as chronic high unemployment, on former President George W. Bush's administration.
On Tuesday night, Strickland will tell how Obama's decision to bail out the struggling auto industry saved vital jobs and kept a mainstay of the U.S. economy afloat, the senior campaign officials said. The goal is to contrast a politically unpopular decision -- spending tax dollars to help a private industry -- in contrast to Romney's call at the time to let General Motors go bankrupt. Romney now says he advocated a managed bankruptcy similar to the eventual result under Obama.
Obama and Vice President Joe Biden have fought back against the GOP attack line, telling supporters that the nation is better off now than it was when their administration took office in January 2009.
In Norfolk on Tuesday, Obama criticized Romney for failing to detail his economic plans, calling them "retreads of the same old polices that have been sticking it to the middle class for years." He cited the 2010 health care reform law he championed and financial industry reforms that followed the Wall Street meltdown of 2008 as examples of accomplishments under his leadership that Romney opposes and has pledged to repeal.
Biden led an effort to sharpen the message of Democrats after other senior party members struggled to formulate a definitive answer to the question of whether voters should feel better off since Obama took office.
"America is better off today than ... when they left," Biden told a Labor Day campaign event in Detroit, referring to the state of the nation the Obama administration inherited from the Bush White House.
"You want to know whether we are better off?" Biden asked, offering a favorite campaign line. "I've got a 'better off' -- Osama bin Laden is dead and General Motors is alive!"
The back-and-forth between the campaigns is part of their competition on how the election gets framed in the minds of voters. Republicans want it to be a referendum on Obama's presidency, while Democrats seek a choice between differing political ideologies on the size and role of government.
In particular, Republicans seek to shrink the size of government and end chronic federal deficits and rising national debt through reduced spending, reforming entitlement programs such as Social Security, Medicare and Medicaid, and slashing taxes on businesses and individuals as a spur for economic growth.
Obama and Democrats argue that a deficit-reduction plan also needs additional revenue as part of the equation, and they propose allowing tax rates on income of more than $250,000 for families and $200,000 for individuals to return to higher levels from the 1990s.
Republicans oppose any kind of tax increase, and the impasse over that issue has been the main impediment to a comprehensive deficit-reduction agreement during Obama's first term.
The race overall is very tight, with a new poll Tuesday showing Romney received little bounce from last week's convention intended to introduce him to voters turning their attention to the presidential race.
The CNN/ORC International survey also indicates that less than 40% of registered voters said the GOP convention made them more likely to vote for Romney. At the same time, Romney got a slight bump in his favorable rating, and on being in touch with the middle class and women, although he still trails Obama on those two questions.
CNN's previous poll, released as the Republican convention got underway, indicated 49% of likely voters backed Obama, with 47% supporting Romney, a statistical tie. In the new survey, which was conducted after the GOP convention, both the president and Romney are at 48%.
"The Republican convention had at best a mild effect on the presidential race, and from a statistical viewpoint, no effect at all," said CNN Polling Director Keating Holland. "Demographically, Romney's overall one-point bounce masks some movement among subgroups and suggests that Romney's pitch to some groups may have worked but at the expense of turning off another group of voters."
While party platforms generally matter little to voters, the contrasts between the versions from this year's conventions showed the Republican adherence to traditional conservative positions while Democrats adopted more mainstream stances generally backed by American public opinion.
The Democratic platform omits a clause from the party's 2008 version proclaiming Jerusalem as Israel's capital, which drew immediate criticism from Romney.
"Four years of President Obama's repeated attempts to create distance between the United States and our cherished ally have led the Democratic Party to remove from their platform an unequivocal acknowledgment of a simple reality," the Republican nominee said in a statement. "As president, I will restore our relationship with Israel and stand shoulder to shoulder with our close ally."
Israelis consider Jerusalem the capital of their country, but Palestinians also claim rights to the city as the capital of a future independent state. The status of the city is designated for final negotiations between Israelis and Palestinians.
American policy has long been intentionally vague on the status of Jerusalem. A U.S. law passed in 1995 designates Jerusalem as the capital of Israel, and stipulates the American embassy should move to the city from Tel Aviv. The past three presidents, however, have signed waivers suspending the law, citing security and diplomatic concerns.
A Democratic National Committee spokesman said that Obama's stance on Jerusalem was consistent with previous administrations.
The omission of the world "God" from the Democratic platform represented a notable difference from Republicans, who mentioned God 10 times in their document approved at last week's GOP convention.
In 2008, Democrats wrote, "We need a government that stands up for the hopes, values, and interests of working people, and gives everyone willing to work hard the chance to make the most of their God-given potential."
Democrats did include a section in their 2012 platform specifically devoted to faith, writing faith "has always been a central part of the American story, and it has been a driving force of progress and justice throughout our history."
A Democratic official pointed out that 2008's reference to God was not specifically about faith, but rather about growing the middle class, and that the 2012 language specifically referring to faith was identical to 2008's document.
Meanwhile, Ryan continued to be hounded by false statements in his convention speech last week, coming out again Tuesday to defend a remark that appeared to blame Obama for the closure of a General Motors plant in Janesville, Wisconsin. An announcement that the plant would close preceded Obama's election.
"What I was saying is the president ought to be held to account for broken promises," Ryan said on NBC. "After the plant was shut down, he said he would lead efforts to restart the plant. It's still idle."
His campaign also confirmed that Ryan misattributed a reference to Reagan's famous question about Americans being better off after four years of Carter, erroneously saying it was in a convention speech instead of the only debate between the two candidates that year, when Ryan was 10 years old.
"I think we can forgive a 10-year-old for mistaking a convention speech and a debate speech and vice versa," said Ryan spokesman Michael Steel.
The Romney campaign proactively reached out to reporters on Monday to point out that, during his Labor Day remarks in North Carolina, Ryan inaccurately described the number of bankruptcy filings under Carter when he was comparing his record to Obama.
Ryan also addressed his erroneous claim to have run a three-hour marathon in the past.
"I thought I ran an ordinary, kind of normal time, and I thought that was an ordinary time, until my brother showed me a three-hour marathon is crazy fast," Ryan responded when asked about the marathon claim in an interview with WTOL. "I ran a four-hour marathon. And so it's just the fact that I did this 22 years ago, and I forgot what my time was and that's what I thought it was."
At a convention breakfast Tuesday, Health and Human Services Secretary Kathleen Sebelius took aim at Ryan over the marathon flap.
"I must confess, I do not do an under-three-hour marathon," Sebelius joked to the Ohio delegation. "Anyone who starts with the notion that you have to make up your marathon time tells you all you need to know about Paul Ryan."