Why the tea party's victories will lead to disappointment

This article originally appeared on Slate.

Meet the new leader, same as the old leader. Rep. Eric Cantor's defeat last week was a message from grass-roots conservatives to Washington's Republican leaders: No more business as usual. But on the eve of the election to replace Cantor as majority leader--the second most powerful person in the House of Representatives--it doesn't look like there's been much of a change in how the House will function.

Rep. Kevin McCarthy, who was in the No. 3 position, is now going to be elevated to Cantor's old post. McCarthy is not an agent of change. On the issue of immigration, for example, which helped inflame opposition to Cantor, McCarthy is even more moderate. (He has in the past expressed support for giving undocumented immigrants a path to legal status.) House Speaker John Boehner, whom grass-roots activists criticize as a capitulator and dealmaker, is more powerful than ever, because without Cantor waiting in the wings, there is less threat that another member of the House could harness his grass-roots critics.

Republicans in Washington got the message after Cantor's surprise loss--just ask the pollsters and

strategists who have gotten calls from newly nervous members. But the limits of the damage caused by the Cantor earthquake were evident shortly after it happened. Conservatives were unable to unite behind a single alternative to McCarthy. Even if they had, they wouldn't have been able to find the votes. Republicans must still legislate, and when it comes to the process of corralling votes and moving legislation--the essential business of legislating--it can't be done by ideological stalwarts and political purists. It must be done by the people who know how to round up votes.

McCarthy's ascension suggests a coming challenge if Republicans take control of the Senate and bring both chambers of Congress under one banner. If that happens, it will be in large measure due to the power of grass-roots conservatives, and yet at the same time it will put the party in a position where compromise and the forces of pragmatism will be stronger than ever. That's likely to cause greater clashes in the running debate between those who promote tactics necessary to govern and those who see those tactics as signs of ideological weakness.

If Republicans win the six seats they need to take control of the Senate, they will owe a debt of gratitude to tea party supporters and other true believers. As the most committed members of the party, grass-roots conservatives will be the ones who turn out to vote in the greatest numbers. Conservative voters will also have played a big role in Republican Senate races in Georgia, Nebraska, and maybe Mississippi, where incumbents will be replaced with conservatives of a more modern flavor.

But if Republicans take control, the party will face a situation not unlike the one House members faced after Cantor's ouster: They will immediately be faced with a set of quick decisions necessary to govern. In the House, that meant electing new leaders, which gave an advantage to those who have skill at leading a legislative body. If Republicans take control of Congress, the advantage will go to Sen. Mitch McConnell and Boehner, men who have been vilified for the budget deals they reached with the president. In those budget deals, both men, and the Republicans who backed them, operated on the theory that the party would be hurt more by getting blamed for government shutdowns and government defaults than by angering the "hell no" caucus. That will be their view after the next election.

If Republicans control Congress in 2015, these fights between the pragmatic and the ideological will be even more pronounced because the pragmatic wing running the show will operate under two theories that will bolster their pragmatism. The first is that they must pass legislation to prove that Republicans can actually govern. Such legislation, even if it is ultimately blocked by a Democratic filibuster or a presidential veto, will require compromises that will be unpopular with tea party conservatives. The second theory is that pragmatists will be worried about looking like they are over-reaching by scoring political points on pet ideological projects, which will hurt the party in the 2016 congressional and presidential elections. That will inspire more caution for fear of turning off swing voters.

In the Senate, there are 24 Republican incumbents up for re-election in 2016. The states Republicans will be defending--Florida, Illinois, Iowa, New Hampshire, North Carolina, Ohio, Pennsylvania, and Wisconsin--will have more diverse electorates than Mississippi or the Virginia district that just ousted Cantor. If Hillary Clinton runs, there are likely to be more women voting in the elections that year. That's not a group with whom Republicans have traditionally done well. Those GOP senators are going to want to run on accomplishments. There will be pressure to pass legislation that will appeal to a broad swath of voters and that affects their daily lives. Such legislation will require compromise.

There will also be pressure not to launch extended show trials into the IRS, Benghazi, and other issues, especially after the vote on repealing Obamacare, which would almost certainly be the first vote in a Congress under Republican control. All of these realities have the potential to irritate core conservatives, who will wonder what good it is to have control if leaders aren't going to stand on principle. The tea party's victories of 2014 may lead to another test for its grass-roots base: either become better followers or purge more leaders.