So just what kind of price would Republicans pay for breaking their pledges and voting to raise taxes?
If history is any judge, it certainly won't help. Above, we look at a Gallup chart of George H.W. Bush's approval ratings at two key junctures during the budget debate of 1990.
The first line is from the end of June, when Bush said for the first time that he would push for a tax increase, in contrast to his previous "Read my lips, no new taxes" pledge. His approval rating dropped from 69 percent to 60 percent by mid-July.
The second line is from mid-September, when budget talks ramped up. Bush's approval rating fell from 76 percent to 53 percent in just more than one month -- a stunning drop, really.
Neither of these drops, we should emphasize, made Bush a pariah. He was still viewed in a positive light by a majority of Americans -- even as his party would lose seats in the midterm election held in November 1990.
And in both cases, the president recovered -- at least temporarily.
But sharp drops in his popularity clearly coincided with whenever his plan to raise taxes was in the news. And of course, by the time he sought reelection, the tax issue really became a liability, with Bush's approval rating sinking into the 30s.
The parallels aren't perfect, of course. As we've written before, most members of the GOP caucus would be more worried about their primaries than the general election.
But it's logical to assume that the people who deserted Bush when he started talking about raising taxes were on the conservative side. And those people vote in GOP primaries.