Kentucky secretary of state Alison Lundergan Grimes is vowing to sue Rand Paul if he tries to run for reelection to the Senate and for president in 2016.

“The law is clear,” Grimes, who lost her Senate bid to Kentucky senator Mitch McConnell earlier this year, told Louisville’s WHAS-11 TV on Wednesday. “You can’t be on the ballot twice for two offices.”

Paul is openly mulling a presidential bid and has already announced that he will seek reelection to his Senate seat. He pushed unsuccessfully last year for the Kentucky legislature to clarify a state law that prohibits candidates from appearing on the same ballot twice. Paul argues that the law applies only to state officeholders and that applying it to federal officeholders is unconstitutional, and he has pledged to fight it in court.

As for Grimes’s threat, the senator’s political team appears uncowed. ”I think we will let her talk by herself,” Paul’s chief political adviser, Doug Stafford, tells National Review Online. Grimes garnered a reputation on the campaign trail for making unforced errors and verbal gaffes, refusing to say, for example, whether she had voted for President Obama.

Whether it is Grimes or Paul who brings the lawsuit, it’s looking increasingly likely that Rand Paul’s presidential campaign will begin in a courtroom. ​