(CBS News) -- Mitt Romney will sweep three Republican primaries in Indiana, North Carolina and West Virginia Tuesday, CBS News projects.
The expected wins bring Romney closer, but not all the way, to the party's nomination, which he is widely expected win.
The former Massachusetts governor now has more than 900 of the 1,144 delegates needed to win the nomination, according to CBS News estimates.
With no serious competition, Romney was able to collect about 100 delegates as he makes his way to the party's official nominating convention in Tampa, Florida at the end of August.
Former rival Newt Gingrich dropped his bid for the presidency last week after announcing the prior week that he would be giving up his White House hopes. Former Pennsylvania Sen. Rick Santorum gave up his run for the White House last month. Santorum endorsed Romney late Monday night in an email to supporters.
Texas Rep. Ron Paul, who has thus far garnered an estimated 89 delegates without winning any contests outright, remains in the race.
Romney has been campaigning vigorously against President Obama and presenting himself as a successful businessman who can lead the country back to economic prosperity.
The two men are in a tight race and likely to engage in a fierce fight for the White House, according to the latest polls.
In a Gallup/ USA Today poll of 12 swing states released this week, Mr. Obama edges out Romney 47 percent to 45 percent -- that's within the poll's four-point margin of error and closer than Gallup's last swing state poll from March, when Mr. Obama held a nine-point lead.
On the critical issue of the economy, Romney has the advantage: In a direct comparison, 47 percent said Romney would do a better job managing the economy, while 44 percent said Mr. Obama would. As many as 60 percent said Romney would do a good job or very good job as president handling the economy over the next four years, while 52 percent said the same about Mr. Obama.