The White House has held meetings in recent weeks with at least three people who may challenge Sen. Jeff Flake, R-Ariz., in his re-election bid next year, according to a report Monday.

Arizona state Treasurer Jeff DeWit, former state Sen. Kelli Ward and former state GOP Chairman Robert Graham are all either considering campaigns or have announced bids, and all have spoken with President Trump or his team about running to replace Flake, Politico reported.

Trump first butted heads with Flake during the 2016 presidential campaign, when the Arizona centrist refused to endorse Trump.

Trump has vowed to fight conservative lawmakers who oppose his work or policies. Flake is now one of a handful of Republican senators undecided on the Senate healthcare reform bill, putting the White House in a tough spot as it tries to court lawmakers for support as it looks to hurt one man’s chances of winning office again.