Republican state Rep. Alan Seabaugh won't run for Senate and instead has backed Rep. Bill CassidyWilliam (Bill) Morgan CassidyTrump signs bills banning drug pricing 'gag clauses' Dem ad accuses Heller of 'lying' about record on pre-existing conditions GOP senator suggests criminal referral for third Kavanaugh accuser's 'apparently false affidavit' MORE (R-La.), the Republican front-runner in the race.

His decision removes a potential impediment to Cassidy's candidacy, which has been dogged by criticism from conservatives and is already facing a possibly problematic challenge from former Air Force Col. Rob Maness, who recently received the endorsement of the Senate Conservatives Fund.

Seabaugh appraised Cassidy as "if not quite a staunch hard-line conservative, at least a solid Republican vote," and said he decided against entering the race to avoid further dividing the Republican vote and jeopardizing chances of taking down Sen. Mary LandrieuMary Loretta LandrieuLobbying world Former New Orleans mayor: It's not my 'intention' to run for president Dems grasp for way to stop Trump's Supreme Court pick MORE (D), a top GOP target.

And he indicated Cassidy's support for a conservative-led strategy to shut down the government in order to defund ObamaCare has helped him with conservatives. Cassidy ultimately voted against a compromise to end the shutdown.

"In recent weeks, Bill Cassidy has proven something to me and fellow conservatives," Seabaugh said, according to the Times-Picayune in New Orleans. "He stood with those of us who care about the future of this country by not giving in to President Obama and the liberal big spenders in Congress. This particular stand was important to me, as a conservative."

Seabaugh likely would've posed a more significant challenge to Cassidy's candidacy than Maness, who has struggled to raise money in his first few months in the race. But a handful of other conservatives, including state Sen. Elbert Guillory, are still toying with the possibility of a run.