For Republicans, the benefits are tempting. If they can pull it off, it’s a two-for-one victory. They will have overhauled the US tax code and taken a bite out of former President Barack Obama’s signature legislative achievement, even if it falls short of the “root and branch” health care repeal many had vowed to see through.

But if they fail, Republicans will enter the midterm election year with their message muddled, without a victory on tax reform, and having spent a year’s worth of time trying and repeatedly failing to dismantle Obamacare with nothing to show for it but bad headlines.

One Senate Republican, Susan Collins of Maine, warned her fellow party members to be wary of diving back into the health care fight and risk capsizing their tax reform efforts just as they were making progress.