WASHINGTON, Dc (CNN) -- As one of a shrinking number of moderate Senate Republicans willing to vote across party lines, Susan Collins is accustomed to enormous attention being paid to many of the votes she casts. After all, her yeas or nays often determine whether key legislation lives or dies.
On Thursday, senators are expected to once again turn their attention to a vote by the junior senator from Maine. This time, though, it's not because the outcome of a bill is in question, but because Collins will cast her 5,000th consecutive vote, a streak she's kept alive since taking office in 1997.
Her milestone is not a Senate record. Former Sen. William Proxmire, D-Wisconsin, holds that with 10,252 straight votes between 1966 and 1988. Sen. Chuck Grassley, R-Iowa, who has cast 6,446 consecutive votes since 1993, is second. Collins is third, after passing about a year ago the 4,705 votes by the late Sen. Robert Byrd, D-West Virginia.
While it would take years for the 59-year-old, third-term senator to catch the frontrunners, the 5,000 mark is still an impressive, Cal Ripken-level achievement. It was earned through determination, perseverance, diligent scheduling and, as she tells it, a willingness to risk bodily injury not to miss a vote.
"At first, I did not have a goal of having a perfect voting record," she told CNN on Wednesday as she stepped off the Senate floor following a routine vote on a federal judge.
But after completing her first two years, Collins said she recognized she had not missed a vote and decided at that point to emulate another Maine senator, Margaret Chase Smith, whose consecutive voting streak went for years before it was ended in 1968 by hip surgery. Smith, with 2,941 consecutive votes, is fifth on the all-time list.
"The people of Maine have a great work ethic, and I think they appreciate the fact that I make such an effort to always be present to cast a vote to represent them," Collins explained. "Now I realize I've been blessed with very good health and I've been fortunate that I've been able to make every vote, but it has taken a great deal of effort, as well."
The closest she came to almost missing a vote was in August 2007 on a run-of-the-mill amendment to an unglamorous small business bill.
Stuck in a lengthy committee meeting in one of the Senate office buildings, Collins said she became "increasingly uneasy" as time ticked by despite promises from the cloak room that the vote would be held open until members of her committee could make their way to the Capitol.
Finally, deciding she could not take a chance, she bolted from the committee room.
"I ran down the steps to the subway, jumped onto the subway. Literally ran up the escalator in the Capitol, twisting my ankle rather badly in doing so because I had high heels on. And when I got to the floor, the cloak room's staff was frantically searching for me and actually had the doors held open.
"I burst in and cast a vote, the very last person to vote. It was after that final question had been posed: 'Is there anyone else in the chamber who wishes to vote or to change his vote?' So it literally was seconds before the gavel fell. And it would have been too late," she said.
"Then, the next 13 members of the committee leisurely arrived over the next 15 or 20 minutes and were furious to learn they had missed the vote," she said. "So I was glad I went with my instinct."
In another close call, Collins said she and Sen. Olympia Snowe, R-Maine, and Sen. Scott Brown, R-Massachusetts, were boarding a flight home at Reagan National Airport when US Airways workers stopped her with an urgent message from the Capitol.
They "burst into the gate area and said 'Stop, don't get on that plane,'" Collins said. "We were literally boarding the plane and (they) told us to get back to the Capitol where there was going to be another unexpected vote."
Speaking of air travel, Collins said she regularly flies from Portland or Bangor to Washington on Sundays instead of Mondays to avoid flight complications that could jeopardize Monday afternoon votes.
"That means sacrificing some personal time," she acknowledged.
It also means sacrificing face time with voters -- even in an election year.
In 2008, when she was running for re-election, she chose to stay in Washington for votes instead of going to Maine for the announcement of a key endorsement by the Democratic mayor of Lewiston, the state's second largest city. It was a hard-earned political prize many senators might have skipped a vote or two to relish.
Over her long streak, there have been a lot of tough votes in which she's endured pleas from both parties to vote with them.
One of the most controversial was the one she cast for President Barack Obama's economic stimulus bill in 2009. She was one of three centrist GOP senators to vote for it, and it would have failed if any one of them voted no. However, in return for her vote, she won concessions from the president and Democratic-controlled Congress to lower the overall price tag of the bill.
Collins says she does not regret that vote.
"I think it's really important to cast your vote and to do so on the basis of the best information that you have at the time, and that's what I did in the case of that vote."
Collins began her Senate career as a staffer for then-Sen. William Cohen, R-Maine, whose seat she would win in 1996. Her first two votes were for Clinton administration appointees Madeleine Albright as the first female secretary of state and Cohen as secretary of defense.
It's not all hard work for the respected and well-liked senator. Her recent engagement to Thomas Daffron, with whom she worked in Cohen's office in the 1970s, is testament that she has a life outside of politics. However, when it came to scheduling her wedding, the senator picked August when the Senate is on a long recess.
Why? She doesn't want to miss any votes, an aide explained.