NASHVILLE (AP) - For U.S. Sen. Lamar Alexander, the elder statesman of Tennessee politics, a primary challenge by a little-known tea party opponent was supposed to be little more than a glorified victory lap around the state.

Instead, the former governor and two-time presidential candidate had to crank up the campaign machinery in the closing weeks of the Republican primary to fend off state Rep. Joe Carr.

And while Alexander ultimately won, it was by just 9 percentage points - a far smaller margin than his campaign and most political observers had expected. The result is giving hope to tea party supporters they could be poised to break the moderate wing of the state Republican Party's decades-long grip on statewide races.

"It is another step in the maturation of the tea party movement," said Ben Cunningham, the president of the Nashville Tea Party. "After the disappointment of losing, I wouldn't call it a euphoria, but lots of confidence about the possibilities for the future."

Cunningham said the results reflected greater coordination between disparate tea party groups, giving activists valuable on-the-ground experience in trying to support a statewide effort.

"A lot was learned just in terms of the nuts and bolts of elections," he said. "That will certainly help going forward."

In the short term, tea party activists hope to focus on local races like those for school boards, where their opposition to Common Core education standards have the most resonance, Cunningham said.

Alexander's campaign cites a number of issues contributing to the closer outcome of the Senate race, including low turnout, complacency among some of the incumbent's supporters and effective messaging by Carr's tea party supporters.

"But bottom line, the anti-Washington sentiment was stronger than we thought," said Tom Ingram, Alexander's chief campaign strategist. "A lot of our voters just didn't turn out."

Ingram said the campaign is still sorting out what it might have done differently and analyzing what the outcome means for the general election campaign against Democratic nominee Gordon Ball and for future statewide races.

That Carr, a little-known state representative, could obtain 41 percent of the vote after being heavily outraised by the incumbent raises questions about what might have been had outside Super PACs not decided to sit out the Tennessee race.

Instead, Carr relied on high-profile endorsements from the likes of talk radio host Laura Ingraham and former vice presidential candidate Sarah Palin, and got a boost from $665,000 in independent expenditures from a PAC controlled by Nashville health care investor Andy Miller.

Carr also sought to energize his campaign by drawing parallels to then-House Majority Leader Eric Cantor's stunning loss to little-known professor Dave Brat in Virginia's Republican primary in June. That race involved a n internal Cantor poll that vastly overestimated the incumbent's advantage, much as an internal Alexander survey trumpeted a 29-point lead over Carr in the weeks before the vote.

Tennessee's junior senator, Bob Corker, is the next incumbent scheduled for a statewide election in 2018. The former Chattanooga mayor has drawn the ire of some on the right who decry his willingness to negotiate with Democrats on key issues and for taking politically difficult stances like supporting an increase in the federal gas tax.

Corker, who has lately been publicly mulling a potential presidential bid, said the week after the vote that he said he was unable to "prognosticate about where the state's going politically," but that he doesn't plan to change his approach.

"I plan to continue to be that person who puts forth commonsense solutions, irrespective of what may be happening," he said.

Gov. Bill Haslam beat several political unknowns to win the Republican nomination to a second term, and faces equally unknown Democrat Charlie Brown in the general election. The governor said a nearly 10-point margin in a crowded field of challengers was "still a pretty good win" for Alexander.

The primary losses of some tea party-leaning state lawmakers, like state Sen. Stacey Campfield of Knoxville and Rep. Tony Shipley of Kingsport, has led to some hurt feelings among like-minded colleagues, who blame Haslam allies for supporting their defeat.

Republican state Rep. Rick Womick of Murfreesboro wrote a letter to Haslam's chief of staff, Mark Cate, decrying what he called "the treasonous targeting" of lawmakers who crossed the governor on education issues like Common Core.

Haslam shrugged off that letter and said he doesn't plan to change his approach.

"I don't know why my supporters should be precluded from doing what everybody else is doing, in terms of being engaged and trying to make certain good people are elected," he said.

Vanderbilt University political science professor John Geer said it may be too early to identify a sea change in Tennessee politics, noting also the failure of a conservative effort led by Republican Senate Speaker Ron Ramsey to oust Democratic Supreme Court justices in the statewide retention votes that were on the primary ballot.

"I think it was a day for the Bill Haslam wing of the party, as opposed to Ramsey's," he said.