Former Trump campaign manager Corey Lewandowski might run in the GOP Senate primary in New Hampshire. (Joshua Roberts/Reuters)

President Trump on Thursday boosted a potential Senate run from New Hampshire by Corey Lewandowski, telling a local radio station that his former presidential campaign manager is “a fantastic guy” who “would be a great senator.”

But the possibility that Trump’s controversial former aide may run for the Senate is prompting heartburn among some in the Republican Party, who fear a Lewandowski bid will complicate the reelection prospects of the state’s incumbent governor and put the New Hampshire Senate race — a lower-tier pickup opportunity for Republicans — out of realistic reach.

During the interview on “New Hampshire Today with Jack Heath,” Trump noted that Lewandowski has yet to announce his plans but said, “I like everything about him.”

At a Manchester, N.H., campaign rally later Thursday, Trump continued to talk up Lewandow­ski’s potential candidacy.

"He's tough and he's smart and I'm hearing he's thinking about running for the Senate from New Hampshire," Trump said of Lewandowski, who had greeted Trump after Air Force One landed earlier Thursday in Manchester. "I think he'd be tough to beat. . . . He'll go into Washington, and he's going to have you in mind."

The rally comments and the radio interview had followed some affirmative retweets from Trump earlier Thursday, when he shared a message from Lewandowski linking to a news story about his plans to appear with Trump on his New Hampshire swing. Trump also shared a news story on Twitter about a poll that purportedly showed Lewandowski leading other Republicans in a GOP primary.

It’s unclear when — or if — Lewandowski plans to announce a Senate run. He said earlier this month that he was looking “very seriously” at a bid to oust Sen. Jeanne Shaheen (D-N.H.) but stressed then that he had no specific time frame. 

The National Republican Senatorial Committee, the Senate GOP campaign arm, has no knowledge of what Lewandowski plans to do, committee officials said.

But GOP officials and strategists have started to warn about the unpredictable effect a Lewandowski bid could have in New Hampshire. The former Trump aide comes with plenty of baggage, including a high-profile run-in with a reporter from Breitbart News that left her with bruises and a lobbying history that his opponents believe is ripe with material.

Lewandowski was also subpoenaed Thursday by the House Judiciary Committee, which wants him to appear Sept. 17 to answer questions in connection with the panel’s obstruction-of-justice investigation into the president. Special counsel Robert S. Mueller III’s report described Lewandowski’s involvement in an effort to persuade then-Attorney General Jeff Sessions to curtail the investigation into Russian interference in the 2016 presidential election.

Some Republicans also said ­Lewandowski could hurt Trump’s bid to win New Hampshire, which he lost to Democrat Hillary Clinton in 2016 by just 2,736 votes. 

“This makes it infinitely more difficult for the president to win reelection in New Hampshire,” said one national Republican strategist working on down-ballot races who spoke on the condition of anonymity to provide a candid assessment. “Every time he goes to the state, he’ll likely be answering for his former campaign manager’s shady business dealings.”

Trump, however, has often been able to weather his own scandals, and it’s not clear how attacks on a former aide would damage him.

Lewandowski would potentially be able to raise a lot money for the race given his high profile across the country with Trump supporters and the close relationship he retains with the president.

In a text message Thursday, ­Lewandowski said it was “very humbling” and “an honor” for Trump to say “such kind words about me.” He declined to confirm any details about a possible Senate run or respond to the internal GOP backlash to his potential candidacy. 

Most of the fretting about a Lewandowski bid is coming from inside New Hampshire, where officials are concerned about the effect it could have on the governor’s race, said GOP officials who spoke on the condition of anonymity to discuss internal party deliberations. 

The state’s governor, Chris Sununu (R), is said to be “exceedingly displeased” with the prospect of Lewandowski running, one of the Republicans said.

A closely contested Senate race could benefit Sununu by helping to drive turnout in New Hampshire, where in 2016 both the Senate candidates picked up more votes than the top of the ticket. 

 “He’s a thug,” former senator Judd Gregg (R-N.H.) told the Union-Leader, the state’s largest newspaper, earlier this month. “He’s part of Trump’s cadre of thugs. If he were to run and become the nominee, it would be an outrage.”

Democrats in the state have already prepared a trove of background research on the former Trump campaign manager’s lobbying efforts, compiled in a 25-page document titled “Lobbyist Lewandowski” that they plan to highlight if he launches a campaign. “Corey Lewandowski is a shadow lobbyist with a nefarious client list that includes foreign interests, which is why New Hampshire Republicans and even Gov. Chris Sununu have been keeping their distance,” Josh Marcus-Blank, spokesman for the New Hampshire Democratic Party, said in a written statement. “Lewandowski, with his record of violence, will make an already nasty Republican primary even worse.” 

Shaheen was reelected to a second Senate term in 2014, with 51 percent of the vote, in a race against Scott Brown, a former GOP senator from Massachusetts who had moved to New Hampshire.

Republicans believe Shaheen is vulnerable under the right conditions, despite her track record as a former governor and a senator who narrowly won in the 2014 midterms, a difficult year for Democrats. 

Granite State poll released this week from the University of New Hampshire found that although 51 percent of voters have a favorable assessment of Shaheen, just 43 percent said she deserves to be reelected and an additional 43 percent preferred a new senator. 

Shaheen’s GOP challenger will be determined in a September 2020 primary. Don Bolduc, a retired Army brigadier general who led a team that rode into Afghanistan on horseback after the Sept. 11, 2001, attacks, has announced a bid, as has Bill O’Brien, a former speaker of the state’s House of Representatives. Attorney Bryant “Corky” Messner is also expected to announce a bid soon.

Senate Majority Leader Mitch McConnell (R-Ky.) has no preferred candidate among those who have declared, according to one of his advisers. 

New Hampshire is considered one of the lower-tier pickup opportunities for Senate Republicans, who are largely playing defense on the Senate terrain next fall. Much more plausible offensive targets for the GOP include Sen. Doug Jones (D-Ala.) and, to a lesser extent, Sen. Gary Peters (D-Mich.).