Most Republicans recognize that their one shot at repealing Obamacare came and went in 2012. But many reports suggest that Republicans would nevertheless send President Obama a repeal bill (or a bill gutting Obamacare) if they take the Senate in November, if only to assuage conservatives.

Because previous Obamacare repeal bills have failed along party lines, everyone takes it as a given that every Republican in Congress would still vote to repeal the law. But there are good reasons to doubt whether that’s still true. In fact, it’s feasible that Republicans could claim control over both houses of Congress next year and still be unable to pass bills that would repeal or hobble the law.

Here’s how Maine Senator Susan Collins, a Republican, responded when asked by Portland’s NBC affiliate whether she’d vote to repeal or defund Obamacare.

“You know at this point, I think we’re past that,” she said. “I think it would’ve been much better if there’d been a bipartisan bill crafted in 2008 that had provisions that both parties could agree on, such as prohibiting insurance companies from discriminating against people with pre-existing conditions. I think at this stage what we should do is a number of bills that would fix flaws in Obamacare. I think we’re past the point of being able to repeal the bill altogether. And as you point out, there are some good provisions in the bill, as well as some that have increased the cost of health care.”

The question of defunding the law is crucial, because unlike full repeal, a bill eliminating the laws financing provisions could theoretically circumvent a filibuster. In other words, you can defund Obamacare with only 51 votes in the Senate. But Republican leaders might not be able to muster 51 votes if they end up with a 51-seat majority, and Collins is their 51st vote.