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The success of President Trump's agenda will also depend on how unified Republicans are in the Senate. That's why all eyes are on Republican Senator Susan Collins of Maine. As NPR's Ailsa Chang reports, Collins has long been the moderate in the middle.
AILSA CHANG, BYLINE: Susan Collins has broken both of her ankles. The left one was when she was sprinting in high heels because she so desperately refused to miss a vote. She has the second-longest voting streak in the Senate, by the way, after Republican Chuck Grassley of Iowa.
SUSAN COLLINS: He has a longer streak, but I'm the only one who's never missed a single vote.
CHANG: Not that she's keeping track. Collins broke her right ankle just weeks ago when she slipped on black ice. And now you'll find her gliding through the halls of Congress in a motorized scooter.
What's the fastest this thing can go?
COLLINS: You'll have to run to keep up.
CHANG: I do. You should try this with the reporters.
COLLINS: (Laughter) I did.
CHANG: These wheels came just in time because Collins is getting chased down by hordes of reporters lately. As a Republican who hovers near the political center, she's once again found herself center stage.
COLLINS: I slow down when people approach.
CHANG: Gentle-mannered and almost always smiling even when she's causing her party headaches, Collins is the Republican vote both sides watch. In a chamber divided 52 to 48 with the most polarizing White House in modern history, Republican Lindsey Graham of South Carolina says it matters more than ever if Collins is a no-vote.
LINDSEY GRAHAM: I think Senator Collins hits above her weight in terms of her influence on the body because she is willing to reach across the aisle. She's not as ideological as a lot of members of the conference. And when you have 52 votes in the United States Senate, it doesn't take much to change the balance of power.
CHANG: That was evident when Collins was 1 of 2 Republicans who opposed Betsy DeVos to be education secretary, which led to the first ever tiebreaker vote by a vice president on a Senate confirmation. Collins is also leaning against drastically changing Senate rules to make it easier for Republicans to confirm their Supreme Court nominee. And on health care, she's co-sponsoring the only Republican bill that gives states the option of keeping Obamacare. Democrats are taking it all in.
DICK DURBIN: We have hope that we can continue to appeal to her. We don't always win our case with her. She's independent-minded.
CHANG: Democrat Dick Durbin of Illinois says Collins will be key if the Senate's ever going to be a check against President Trump.
DURBIN: She has the courage to step up and do things that are unpopular. Many on the other side do not.
CHANG: Last November, Collins wrote in House speaker Paul Ryan for president. She now says she does want to see Trump succeed, but she's spoken out against him many times already, including against his executive order on refugee resettlement.
Under a Trump administration, does your willingness to work with the other side take on a greater purpose? Is it more than politics at a time like this?
COLLINS: Our country is more divided than any time I have ever seen, and I'm very concerned about that. I feel a special obligation to try to find a path forward on the many contentious issues that we're facing.
CHANG: Collins says being the deciding vote is nothing new. She's been a moderate throughout her 20 years in the Senate. But the spotlight is a lot more intense these days.
COLLINS: I do feel more pressure. I can't tell you the number of people in Maine and elsewhere who have come up to me and have said to me, are you going to be there for us? Are you going to protect us?
CHANG: She's literally caught in the middle. In northern Maine, Trump won by 11 points. In southern Maine, Hillary Clinton won by 14 points. It's a state that's produced a long line of moderate politicians. But the other senator from Maine, Independent Angus King, says being moderate now is so much harder.
ANGUS KING: Because people from both sides are so passionate. You know, if you're not a hundred percent for me, you're against me. And it - people are being pulled to the edges. You rarely see huge rallies of moderates (laughter).
CHANG: But in the Senate, it takes only a handful of them to change any outcome. Ailsa Chang, NPR News, the Capitol.
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