PORTLAND – Sen. Susan Collins has gone to great lengths to preserve her unbroken voting streak in Washington.

On one occasion, it meant deplaning from a commercial flight to race back to Capitol Hill. Another time, she twisted her ankle as she scampered down marble hallways to the Senate floor with moments to spare. She even scheduled her upcoming wedding for the August recess, just to be safe.

The Maine Republican has never missed a vote since taking office in January 1997 — a record that evokes comparisons to baseball great Cal Ripken. This week, she expects to make her 5,000th consecutive vote.

She says her voting record resonates with Mainers.

“It demonstrates to my constituents my unwavering commitment to my job. I also think the people of Maine have a great work ethic and that they relate to it. They’re very diligent about showing up for work and meeting their obligations. They’re happy that I feel the same way,” Collins said.

Among sitting senators, only Republican Chuck Grassley of Iowa has a longer voting streak, having cast 6,444 consecutive votes dating back to 1993, when he missed votes to join President Bill Clinton in touring flood damage in Iowa. Grassley said his voting record shows he’s “not horsing around” while he’s in Washington but, unlike Collins, he can’t claim that he never missed a vote. Collins’ record stood at 4,997 votes as the Senate prepared to reconvene.

Impressive as their records are, Grassley and Collins pale in comparison with the Senate’s record holder, Wisconsin Democrat William Proxmire, who had 10,252 consecutive votes from April 20, 1966, to Oct. 18, 1988.

Collins’ unblemished record tracks that of her mentor, the late Sen. Margaret Chase Smith, who never missed a Senate roll call in 13 years before surgery ended the streak at 2,941.

“She was a stickler about it,” said David Richards, director of the Margaret Chase Smith Library in Skowhegan.

Collins has had several close calls, including the time in 2010 when she and Sen. Olympia Snowe were recalled to the Senate floor after boarding a flight home.

But the closest came during a Homeland Security Committee meeting in 2007. Collins received assurances from Sen. Joe Lieberman of Connecticut, who’d been told by Democratic leadership that a Senate floor vote would be held open for committee members.

Feeling uneasy, Collins slipped out of the committee meeting and soon ended up in a foot race against the clock. “I jumped on the subway, ran up the escalator and literally twisted my ankle because I was running in high heels,” she said.

The Senate door was held open when she raced inside to cast the final vote.