Before the polls closed in Kansas yesterday, I predicted that the Republican primary for the US Senate race would be closer than people expected. The incumbent, Sen. Pat Roberts, hadn’t spent much time at home of late — and may not even own a home there at all any more — and losing touch with constituents was what doomed Eric Cantor. Roberts won, but only by single digits against his Tea Party challenger:

Veteran Republican Senator Pat Roberts fought off a Kansas primary challenge by a Tea Party-backed doctor who had promised a “family feud” with his distant relative President Barack Obama if elected, results on Wednesday showed.

Roberts secured 48 percent of the vote and Milton Wolf 41 percent in the four-candidate field, according to final but unofficial results, the Kansas secretary of state said.

Roberts has had a 47-year career in Congress and faced conservative challenger Wolf, who said he wanted to “save the Republic.”

Wolf acknowledged a distant family tie to Obama but built his campaign on promises to repeal many of the Democratic president’s policies. In an interview with CNN, Wolf promised “the mother of all family feuds to save America,” if elected.

Roberts didn’t even get to 50% in a state he’s represented for decades, against a novice candidate. He’ll win re-election easily in November, though; more than four times as many voters turned out in the GOP primary than in the Democrats’ competitive Senate primary. Democrats have a huge enthusiasm problem, and not just in Kansas, either.

The media line has been that this year’s results are a defeat for the Tea Party. Both CBS News and The Hill ran articles yesterday on the “fade” of the Tea Party, and today’s New York Times takes a more subtle approach to the same theme:

Senator Pat Roberts of Kansas held off the Tea Party insurgent Milton Wolf on Tuesday to defeat what may have been hard-line conservatives’ last chance at knocking off an incumbent Republican senator this year. …

The primary in Kansas on Tuesday, as well as the votes in Michigan and in Washington State, proved to be more about the power of incumbency than the Republicans’ civil war.

Tea Party incumbents generally held off challenges from establishment Republicans, and establishment incumbents beat back challengers from the right.

Well, maybe, but it’s far too early to declare the Tea Party dead. In my column for The Week, I argue that the Tea Party is a long-term phenomenon that is already succeeding in forcing the Republican Party and its incumbents to define themselves in terms of small-government conservatism:

The true test of the Tea Party won’t be in primary victories this week or this year, but in the impact of the conservative grassroots movement on the Republican Party. We have already seen incumbents who have rarely if ever had to deal with intraparty challengers shift their focus and message in response. The lack of banner wins in 2012 certainly didn’t persuade most of these incumbents to dismiss that pressure — in fact, the ones who succeeded most were the ones who prepared soonest and most vigorously.

When the New Left brand of progressivism arose in the 1960s, its candidates didn’t win a lot of elections at first either. It took two decades for the pressure of the movement to shift the center of the Democratic Party away from its traditional, blue-collar liberalism. In the late 1980s, the trend worried Democrats enough to form the Democratic Leadership Council to push back and recruit moderates to run for office, the most successful of which was Bill Clinton in 1992. By 2008, his wife blew her opening for the presidential nomination in part by falling short of the progressive credentials of Barack Obama.

The lesson here is not to count primaries in the short run. Look for the way incumbents have to defend their record, and wait for the grassroots to produce change organically over the long run.

We’ll also see Lamar Alexander defending his Senate seat tomorrow against Rep. Joe Carr, who picked up an endorsement from Laura Ingraham. Alexander routinely gets criticized by the grassroots, but he’s also been taking a page from Lindsey Graham and putting in plenty of retail-politicking effort in Tennessee over the last couple of years. There has been very little polling in this race, but what there has been looks similar to Kansas — the incumbent up by low double digits but looking vulnerable. Even if Alexander manages to survive, though, it won’t be because voters have rejected the Tea Party but because the incumbent has embraced it.