This post is part of Polyarchy , an independent blog produced by the political reform program at New America , a Washington think tank devoted to developing new ideas and new voices.

If Republicans continue to face defeats and worse-than-expected outcomes in special elections this spring, as they did in Kansas’s deep-red Fourth District, they have at least one big advantage: a very early warning of the electoral debacle facing them in 2018, if things remain on their current course.

Midterm elections have brought losses to the president’s party in 18 of the past 20 cycles, averaging more than 30 seats in the House, although with wide variations. While the biggest reversals seem inevitable in retrospect, in the moment they often came as a surprise, even with just a month or so to go. While the backlash to Barack Obama built slowly over the course of 2009, Democrats did fine in all the special elections that year. Ted Kennedy’s Massachusetts seat was lost to Scott Brown only in mid-January 2010. It was not until the summer of that year that the magnitude of likely losses was widely predicted.

Nor was the magnitude of the risk to the president’s party clear this early in the 1994 cycle, when Newt Gingrich’s Republicans took advantage of the backlash against Bill Clinton to take control of the House for the first time in four decades. Republicans’ disadvantage on the “generic ballot” (which party’s congressional candidate would you vote for?) is wider than it’s ever been in the first half of the year before the election. At this point in 1994, Democrats still had an advantage in the generic ballot, as did Republicans a few months after George W. Bush’s reelection in 2005. No president has slid as fast and as far as Trump, from a historically low starting point.

Equipped with this warning, what will Republican members of Congress do? That question is relevant not only to the distant election but to the behavior of at least some of them between now and November 2018 — on taxes, debt limits, and all the other issues they’ll have to deal with. “If you’re an incumbent Republican member of Congress, this is an indication you need to be executing the fundamentals back home,” a Republican consultant named Ken Spain told Jonathan Martin of the New York Times.

What does “executing the fundamentals” mean? For decades, members of Congress have protected themselves from unpopular presidents, popular presidents of the other party, or broad discontent by lavishing attention and usually money on their districts and their constituents. That attention is at the root of the idea that people hate Congress but love their individual member.

Democrats elected in the post-Watergate wave of 1974 often defeated older incumbents who had lost touch with their constituents, and thus learned to invest time and money in constituent service, including casework and frequent town meetings and public forums. That approach helped many of them survive for decades even as their constituents supported Ronald Reagan and other Republicans.

When Gingrich’s Republicans unseated those and other Democrats in 1994, the new speaker encouraged the use of earmarks — spending tagged by Congress for specific projects — to help them solidify their position in vulnerable districts. Earmarks grew starting in 1995, and their use peaked in 2005, just as Republican members needed protection from the growing unpopularity of George W. Bush. (The “Bridge to Nowhere” — an earmarked appropriation for a project in a little-populated area of Alaska — dates from 2005 and became a symbol of the practice for years thereafter.)

Earmarks also helped ruthless House leaders such as Tom DeLay round up votes on their priorities, such as passage of the Medicare prescription drug benefit in 2003. They became a kind of small-denomination currency that enabled all the little deals that made Congress function, sort of, despite the emergence of sharp ideological polarization.

But the most ideologically committed Republicans abhorred the practice, considering it a symbol of reckless spending even though earmarks had no real impact on total spending. Others, not limited to the House Freedom Caucus, saw it as symbolic of the endless compromises on taxes and spending that prevented the full realization of conservative priorities.

And so, within weeks of the 2010 election, Republicans eliminated the practice of earmarking. Some political scientists and journalists made a bit too much of this change as the primary cause of the gridlock of the Obama years, suggesting restoration of earmarking alone would unlock the gears of government, as well as minimizing the consequences of such petty corruption.

But the problem wasn’t that Congress didn’t possess these transactional tools; it’s that a majority of the members, primarily in the majority party, didn’t want them. They bound themselves to the mast of ideological purity. They had concluded that there was more to gain from admitted demands, unshaken by the petty claims of constituents and colleagues, than from ordinary transactional politics.

Many Republicans, including governors, went further, rejecting large infrastructure projects and the nearly cost-free expansion of Medicaid under the Affordable Care Act. A few members of Congress even declared publicly that they wouldn’t help constituents with Affordable Care Act problems. This rejection of transactional politics, more than partisan polarization alone, distinguishes the Obama period from the decades before it.

But with one notable exception (the obstruction of compromise pick Merrick Garland’s nomination to the Supreme Court and replacement by the unwavering Neil Gorsuch), this brand of politics hit its limits in 2016 and ’17. Most recently, the backlash against repeal of the ACA, fueled by angry town hall meetings and congressional office visits, should have reminded members of Congress that their constituents were as interested in tangible benefits from government as they had ever been. But even before that, the success of the Trump campaign, which replaced the ideological absolutism of, say, Ted Cruz or Paul Ryan with a weirdly technocratic promise to fix problems and deliver benefits, should have shown the exhaustion of purely ideological politics.

So in theory, the field is open for some Republican members, maybe only the most vulnerable 25 or 35, to find their way back to transactional and local politics, the small trade-offs and compromises, not just across parties but across regions, local industries, and special interests that have always allowed politics to function. Strangely, though, the politician whose campaign showed the limits of ideological purity passed up the opportunity to take advantage of this made-for-Trump development.

Trump’s proposed budget strips away not just earmarks but virtually all the underlying programs, such as Community Development Block Grants, that allowed members of Congress to direct funds to local governments and nonprofits. He embraced the most radical version of ACA repeal. By bringing the most absolutist members of Congress into his administration, such as Office of Management and Budget Director Mick Mulvaney, Trump divorced himself from his own presumptive strength — wheeling and dealing in a steady flow of dollars.

But his budget was so far out of line with even the conservative norm that it is likely to have little impact on the actual federal appropriations bills that will eventually emerge, probably after a series of showdowns about shutting down the government and with only modest changes to spending. That means members of Congress who want to return to fundamentals — putting their districts and constituents ahead of ideology, for political reasons — might find some room to do so. Whether it will work remains to be seen; it may be that politics is so nationalized, and so many districts so safe, that either most members will have no electoral worries at all — in a primary or a general election — or nothing will protect them from the sinking Trump brand.

It’s also possible that congressional Republicans will think “fundamentals” means diverting attention from Trump by reopening old fights from the Obama era. Rep. Kevin Brady, for example, recently suggested revisiting the largely fictional “IRS scandal” of 2011, and calling back the overwhelmed bureaucrat Lois Lerner to testify again. (Those were fun times, for congressional Republicans!) Or they may assume that just a little rhetorical distance from Trump will be enough to protect themselves.

But if they behave like politicians of the 1970s, ’80s, ’90s and even the past decade did, when trying to reconnect to their own voters, it’s possible they will restore some of the transactional politics that, sometimes, made it possible to get bigger things done. And if even a critical few recalibrate their approach, the Trump backlash could lead to a deeper behavior change, and a reminder that the norms and practices of American politics are never fixed and can change abruptly, even faster than partisan alignments do.