Beleaguered Tennessee Democrats are re-examining next year’s U.S. Senate election after Republican Bob Corker’s decision to retire has brightened their outlook for a race that's still considered a long-shot for them to win.

Democrats haven’t won a U.S. Senate election in Tennessee since Al Gore was elected in 1990.

During the two weeks since Corker announced he won’t seek a third term, three of the party’s up-and-comers have looked at the 2018 race. One, state Sen. Jeff Yarbro of Nashville, said over the weekend that he won't run, while Chattanooga Mayor Andy Berke continues to mull a Senate bid. State Rep. John Ray Clemmons of Nashville said he isn't ruling out a run either.

More:President Trump's threats may start 'World War III,' Sen. Bob Corker says

Meanwhile, declared Democratic candidate James Mackler — who some Democrats say is already the most viable candidate their party has fielded in multiple cycles for Senate — says he's pressing forward with his campaign regardless if other Democrats enter. Mackler, a Nashville attorney and an Iraq War veteran, announced his candidacy in April.

A 'political earthquake?'

The renewed buzz on the Democratic side is a sign party leaders believe the stars could align for a competitive race now that the establishment Corker — who was the heavy favorite — is no longer in the picture, and the conservative flame-thrower U.S. Rep. Marsha Blackburn, R-Tennessee, is the new front-runner.

The open Senate race coincides with an open governor’s race next year, the first time that has occurred in Tennessee since 2002. Former Nashville Mayor Karl Dean and House Minority Leader Craig Fitzhugh are seeking the Democratic nomination for governor.

More:Sen. Bob Corker will not seek re-election next year

To put both races in play, Democrats hope to capitalize on a midterm revolt nationally against President Donald Trump — a scenario that is far from a guarantee, especially in Republican-dominated Tennessee, even though the president's poll ratings have lagged nationally.

"This is a political earthquake,” Lisa Quigley, chief of staff for U.S. Rep. Jim Cooper, D-Tennessee, said after Corker’s exit. “Having two open, statewide races is a rare occurrence in Tennessee. The opportunity for Democrats is to field common-sense, inspiring leaders who can unite the state and move us forward.

“At the same time, Republicans will be nominating people who are running to the extreme, far right on issues that impact people's lives like health care, infrastructure, taxes, and civil rights. The choices could not be more stark or consequential.”

Democrats size up Blackburn as GOP front-runner

Democrats had been less optimistic about their chances when there was a possibility of Republican Gov. Bill Haslam, an establishment moderate, entering the Senate race.

More:Who will jump in race to replace U.S. Sen. Bob Corker? Intrigue starts with Haslam, Blackburn

But with Haslam declining a Senate bid, some see a chance to pit a business-minded, centrist Democrat against Blackburn, who came out of the gate with an online video that was an unabashed play to Trump’s Tennessee base.

“Rep. Marsha Blackburn’s announcement went just about as far right as a candidate can go,” said Kent Syler, a political science professor at Middle Tennessee State University. “She clearly is trying to position herself in the Republican primary so that no one can get to her right. And her calculation is the Republican Party primary is all that matters because the Democrats don’t have the ability to win an election in Tennessee.

More:Does Marsha Blackburn's entry into the Senate race clear the GOP field?

“The question is, is she right or wrong?” he said, adding that she's left a lot of political playing field vacant. “Can the Democrats find a candidate and are there enough Democratic votes left and can that Democrat candidate appeal to the majority of independents and maybe peel off moderate Republicans? That's what it takes."

Former Republican U.S. Rep. Stephen Fincher is beginning a statewide listening tour this week as he mulls a bid.

Berke says decision on Senate run coming soon

Berke, a former state senator who was re-elected to his second term as Chattanooga mayor earlier this year, has shown the most visible signs of perhaps mounting a run. Last Sunday, he held a “supporter conference call” to discuss a possible run. Berke said he will make a decision “relatively quickly.

More:Chattanooga Mayor Andy Berke mulling Democratic Senate run to replace Corker

“I think I have something to add to the debate, and right now it’s a question of whether I’m going to end up in the race,” he said, adding that voters want to see an a government “united in purpose to try to build our economy and grow our middle class.

“There are more people receptive today to that message. I think that’s why a Democrat who can articulate how he or she will affect that can make progress.”

Yarbro rules out Senate bid after considering

Yarbro, in deciding against a run, said, "My work right now is in Tennessee." Yarbro, who faces re-election next year, would have had to give up his state senate seat to run for the federal office.

"The government in Washington is embarrassing right now, and I believe that all of us know in our gut that this is a time that requires more of us as citizens," he said

More:Democratic state Sen. Jeff Yarbro considers run for U.S. Senate to replace Corker

"I think 2018 is shaping up to be a great year for Tennessee to elect a Democrat with common-sense. I'm looking forward to supporting rather than being that candidate."

Clemmons, a second-term House member, said he plans to continue traveling around the state to talk to Tennesseans and would make a decision before the holiday season.

"We're going to be popping around the state and talking to folks making sure the Democratic Party has the best possible option in that U.S. Senate race," Clemmons said.

Mackler says he's running in primary regardless

Since the Corker announcement, the Mackler campaign has set out to remind Democrats that Mackler already has an operation in place, and that he stepped up when it appeared the Democratic nominee would be taking on Corker. Claiming momentum, Mackler announced last week that he's raised more than $750,000 for his run.

In a campaign fundraising email, former Tennessee Democratic Party chairman and 2008 U.S. Senate candidate Bob Tuke doubled down on his support for Mackler after speculation grew about new Democrats looking at Corker's seat. Tuke said it took "courage" for Mackler to run, adding: "Now, with Sen. Corker retiring, we have an opportunity to send a real leader to the U.S. Senate."

More:Democrat challenger raises $451,000 in Senate run against Corker

"We live in a democracy," Mackler said. The great thing about that is if anybody wants to run for office, can run for office. None of that makes any difference for my plans.

"I got into this race six months ago against a popular, well-known senator when people said there's no way that you can win this race because I saw what was going wrong in Washington because I do what's right, not necessarily what's easy."

From 'solidly' to 'likely' Republican

Tennessee Democrats last fielded a competitive U.S. Senate candidate in 2006, when then-U.S. Rep. Harold Ford Jr. of Memphis lost to Corker by 3 percentage points. In 2014, Democrat Gordon Ball lost to U.S. Sen. Lamar Alexander by 30 percentage points.

Some Democrats point to the statewide wins of former Gov. Phil Bredesen in 2002 and 2006, but Democrats haven't succeeded in a statewide race since.

Still in a sign of better odds for 2018, The Cook Political Report, led by political analyst Charlie Cook, moved the Tennessee Senate Race from “solidly Republican” to “likely Republican” after Corker’s decision. To win back the majority in the Senate, Democrats need to pick up three seats.

"Any Democrat would start the general election as an underdog, but national Democrats have good reasons to take this race seriously, not the least of which is that they need a third target if they hope to have even the remotest shot at the majority, the Cook Political Report's analysis says. "The possibility that Republicans could hold a brutal primary that may produce a less than ideal nominee provides more incentive."

More:Democrat Bill Freeman rules out U.S. Senate run; pushes Phil Bredesen as candidate instead

Bredesen has said he's not interested in running for U.S. Senate despite some Democrats pushing him to run.

“With Corker stepping down, the chances of Democrats taking the Senate seat went from less than a percent to probably about 20 percent at least," said Vanderbilt University political science professor John Geer.

"If (the Republican nominee) has to campaign to the extreme to get the nomination that gives the Democrats an opening, especially the kind of candidate that Bredesen represents," he said. "I don't think Bredesen will run, but he's the kind of candidate that can win a statewide race."

Other political observers believe the dynamics in Tennessee have tilted so much in favor of Republicans that the past Bredesen performances are no longer relevant.

Tennessee Democratic Party chairwoman Mary Mancini said Democrats were energized for the Senate race before Corker's decision and that, while his move changed the dynamics, the party was confident they would be competitive regardless.

Mancini called Mackler an "excellent candidate" and called it "inspiring" that Democrats have leaders with futures ahead of them. She said if there's a contested primary, it will be a "contest of ideas" and a "sharp contrast to the ugliness we have become accustomed to seeing on the Republican side."

Reach Joey Garrison at jgarrison@tennesesan.com, 615-259-8236 and on Twitter @Joeygarrison.