Hours before President Biden announced he would not seek reelection, Republican House Speaker Mike Johnson said there could be legal challenges — a warning election law experts said would only hold true if Biden was the official nominee.

“Every state has its own election system,” Johnson told CNN’s Jake Tapper Sunday on “State of the Union” — hours before Biden’s announcement. “In some of these states it’s a real hurdle replacing someone at the top of the ticket.”

The ticket, however, is not official until the end of the Democratic National Convention, set for next month in Chicago. Election law experts said changes made before then do not pose legal challenges.

“Joe Biden was never the official nominee of the Democratic Party,” election law expert Rick Hasen told the Daily News in an email Sunday evening. “So long as Democrats timely pick their candidates, the chances of any legal challenge to their presidential and vice-presidential candidates appearing on the ballot is incredibly small.”

The “election system” issues Johnson referred to come into play if the nominee is changed after the deadline for naming an official nominee and if ballots have already been printed, according to a scenario reported Friday by Iowa Capital Dispatch. Those deadlines are mostly in August or September.

Johnson nonetheless also implied potential subterfuge on the part of Democrats.

“Joe Biden was chosen after a long, ‘small-d’ democratic process by 14 million people emerging through that primary,” Johnson told Tapper. “It will be interesting to see if the so-called party of democracy, the Democrats, go into a back room somewhere and switch it out and put someone else at the top of the ticket. I think they’ve got legal hurdles in some of these states, and it would be litigated I would expect on the ground there, and they’ll have to sort through that.”

The Democratic party has promised anything but a “back room” process.

“In the coming days, the Party will undertake a transparent and orderly process to move forward as a united Democratic Party with a candidate who can defeat Donald Trump in November,” DNC Chair Jaime Harrison said in a statement after Biden’s announcement. “This process will be governed by established rules and procedures of the Party. Our delegates are prepared to take seriously their responsibility in swiftly delivering a candidate to the American people.”