FRANKLIN, Tenn. — The Republican Party expanded its majority in the U.S. Senate in Tuesday’s divisive midterm elections, riding a Trump train fueled by red-state enthusiasm right through the rough political headwinds that knocked the GOP from power in the House of Representatives.

At odds last year after the Obamacare repeal effort collapsed, President Trump and Republicans in the Senate made amends, coalesced around a historic $1.3 trillion tax overhaul, and united for the 2018 fight. The race unfolded amid a toxic environment Republicans hadn’t experienced since 2006, when a blue wave sank their congressional majorities, leaving them anxious that an electoral map dominated by ruby red battlegrounds wouldn’t save them.

[Byron York: For Trump, challenge of governing with Dem House, but full speed ahead with GOP Senate]

Trump commands legions of #MAGA voters more loyal to him than the GOP, and the pact between the president and Senate Republicans would prove fruitful. Wednesday morning, Republicans had control of 51 seats, and were poised to hold as many as 54 depending on the final outcomes in Arizona, Florida and Montana. Thus far, the Democrats have only managed to flip one seat, to oust Sen. Dean Heller, R-Nev.

Earlier this fall, with a spark lit by a week of explosive hearings to confirm conservative jurist Brett Kavanaugh to the Supreme Court, Trump leveraged the fidelity of his followers to make the case for unknown Republican Senate candidates in series of high-octane rallies down the stretch of the campaign, putting battle-tested Democratic incumbents with more resources on the defensive.

The president's strategy ultimately put the Democrats' outside shot at winning the majority out of reach.That’s how it played out in Tennessee, where Trump won two years ago by a whopping 26 percentage points.

Republican Rep. Marsha Blackburn easily defeated Democrat Phil Bredesen, a popular former governor in a contest considered key to the GOP maintaining, and padding, a slim 51-49 majority. Bredesen executed a near picture perfect campaign, and Blackburn only solidified her lead in the race after the Kavanaugh hearings and two presidential rallies in the Volunteer State juiced Republican engagement.

Marcia Clark, a Blackburn supporter, said Trump had a direct influence on her vote. “He asked us to support her, and that’s really how we came to know her so well is by paying attention to what he asked us to do,” said Clark, a middle-aged business owner from Clarkesville, an exurban community about 60 miles northwest of Nashville.

“Our president has made such a difference already, he’s energized the Republican Party again. It’s so exciting to see that happen and he’s making a difference all across the board, in the economy, in immigration,” she said.

Republican challengers ousted Senate Democratic incumbents in Indiana, Missouri and North Dakota, three states that Trump won comfortably. In Florida, a swing state where the president scored a narrow 2016 victory, the GOP was waiting on the possibility of yet another pickup. Blackburn’s win in Tennessee was a GOP hold — she replaces retiring Sen. Bob Corker. But her race revealed Trump's pull in states dominated by GOP base voters.

Projected to win for several weeks, Blackburn cruised beyond what her confident campaign was privately predicting hours before the polls closed. The contest was called early Tuesday evening, and the senator-elect was garnering just under 55 percent of the vote, and beating the formidable Bredesen by double-digits with most precincts reporting.

Blackburn singled out Trump and Vice President Mike Pence for a “special thank you” during the victory speech she delivered at a suburban Nashville hotel, where a raucous crowd joined her to celebrate the victory. When did Blackburn feel that she the race in hand?

It began after Labor Day, with her first debate with Bredesen, she said in an interview with the Washington Examiner in her hotel suite minutes after the race was called. “Shortly after that, you have the Kavanaugh hearings, and then it was followed by the president going to upper East Tennessee,” she added, referring to the #MAGA rally Trump held for her in Johnson City. “Those three things really got the movement started.”

Voter turnout was up across the nation, higher than usual for a midterm election, with Republican energy nearly matching the supercharged Democrats, who were poised to capture the House in a series of close contests that were sweeping the GOP from power in affluent suburbs from coast to coast.

That leveling of partisan participation put the Republicans in a position to capitalize on a favorable Senate map that featured 10 seats on the ballot in states that Trump won two years ago. The usual platitudes — about raising money and moving early to negatively define Democratic incumbents and challengers in contested states — were offered to explain GOP success.

But GOP strategists intimately involved in the campaign to hold the Senate said that the party's ability to use friendly battlegrounds to grow its majority was actually the product of key developments and decisions made by the top brass at crucial points during the two-year cycle.

More than any other, Republican operatives in separate interviews said that recruiting Rep. Kevin Cramer into the North Dakota Senate race was critical. The Republican initially spurned Trump’s entreaties to take on Sen. Heidi Heitkamp, D-N.D., after which Republicans, with a surprisingly thin bench worried they wouldn’t be able to dislodge the incumbent despite the state’s strong GOP lean.

But Trump and his political deputies at the White House; Senate Majority Leader Mitch McConnell, R-Ky.; and Sen. Cory Gardner of Colorado, chairman of the National Republican Senatorial Committee, continued to push Cramer to take on Heitkamp in the weeks after he said no, pitching him and his wife in one-on-one conversations, and he and his wife together, to reconsider.

The effort paid off, and Republicans believed after Cramer entered the race that a massive blue wave would have to develop for the Democrats to erase their majority.

"It's tough to win seats in a midterm,” Chris Hansen, Gardner’s top lieutenant at the NRSC, said, explaining the historic difficulty of picking up seats in a midterm election when the party in charge of Congress also holds the White House. “If we didn’t have Cramer, it would have been a whole different ballgame."

Another factor cited was Trump's sidelining, and then firing, of Steve Bannon, his nationalist chief strategist who hoped to use his White House perch to foment a revolt against McConnell and his leadership team.

Bannon’s utter disdain for majority leader, and in fact the near entirety of the Republican establishment, was viewed as the chief reason for the intraparty feud between Trump and Senate Republicans that persisted for most of his first year in office and played out on Twitter almost daily. As Bannon's influence with the president waned, and then ended altogether with his ejection from the West Wing, the relationship between McConnell and Trump improved.

Trump would end up endorsing every Senate GOP incumbent on the 2018 ballot, including Heller, a previously vocal critic.

How Trump handled the Kavanaugh nomination after multiple women accused him of sexual misconduct is viewed as the third pillar of Republican Senate gains. The allegations against Kavanaugh were never corroborated and the president stuck with him through a volatile confirmation process that didn’t always look like it would succeed, never mind accrue political benefits. That decision, GOP insiders say, may have single-handedly saved the majority.

“If Trump doesn’t stick by Kavanaugh we get wiped off the map,” said Republican strategist Brad Todd, who advised the NRSC this cycle and also steered GOP state Attorney General Josh Hawley’s defeat of Democratic Sen. Claire McCaskill in Missouri. “Voters would have stayed home because we would have given up to the Democrats — it would have been Obamacare repeal all over again.”

On Wedesday, Republicans were still waiting for final results from Arizona, a Republican-held open seat and a tough battleground with significant blocs of the same suburban voters that threw the GOP out of power in the House. Senate Republicans also were waiting on Montana, yet another pro-Trump styled Republican stronghold.

Victories in both might push the Republican majority past even the party's rosiest scenarios considering the difficult atmosphere that prevailed nationally.

Indeed, those conditions contributed to the surprising level of Democratic strength in Senate races across states with that Trump won two years ago because his personality and agenda had broad appeal there. That includes West Virginia, with Democratic Sen. Joe Manchin surviving re-election in a state that produced among the president's largest victory margins in 2016. Also: Ohio, Pennsylvania and Wisconsin.

Each of the Democratic incumbents on the ballot in these states is unabashedly progressive, and yet each won going away. Justin Barasky, who managed Democratic Sen. Sherrod Brown's campaign in Ohio, said the key to his party's success in states that support the president and many elements of his agenda is to show up in every community, and pay attention to the concerns of working class voters.

Brown, an old school liberal, has much in common with the president on issues like trade and getting tough on China.

"Democrats can win in Trump states by focusing on the dignity of work and fighting for everyone — not some," Barasky said. "Sherrod Brown has spent his career putting workers first while not compromising on civil rights, women’s rights, or social justice and that was the focus of our campaign."

