A bipartisan group of former lawmakers is warning No Labels that its third-party presidential campaign might cause a "constitutional crisis" by throwing the election into the House of Representatives.

Why it matters: Most of the previous criticism of No Labels has focused on its perceived weakness, raising the possibility that it could siphon off just enough votes from President Biden in key states to tip the election to former President Trump.

Zoom in: The new line of attack acknowledges the potential strength of a No Labels ticket — and the prospect that it could win a handful of states outright.

• That would translate into actual votes in the Electoral College. If the two major party candidates are each kept under 270 electoral votes, the newly elected House would choose the president in 2025.
• In a "contingent election," the 12th Amendment gives each state one vote for president. The Senate selects the vice president.

Driving the news: In a letter to No Labels' leaders, former lawmakers — including Sens. Doug Jones (D-Ala.) and Jack Danforth (R-Mo.) and former House Majority Leader Richard Gephardt (D-Mo.) — are warning the process could get messy.

• "A No Labels presidential ticket could produce a constitutional crisis by triggering a 'contingent election,'" they wrote in a letter obtained by Axios.
• "Because the procedures are not set in the Constitution, the party with a narrow majority in the House at the start of the 119th Congress could, no doubt, adopt biased rules that advantage their favored candidate — even if the voters clearly preferred someone else," they write.
• "A contingent election would be calamitous."

Zoom out: With Trump and Biden both winning their parties' early contests, a rematch is looking increasingly likely.

• No Labels, founded by Nancy Jacobson in 2010 to advocate for centrist policies, has been arguing that voters don't want a repeat of the 2020 campaign and deserve an alternative option.
• The group is moving forward with its efforts to gain ballot access in all 50 states, with plans to make a formal announcement on whether to field a ticket by the middle of March.
• It has decided to scrap its nominating convention. Organizers haven't explained how it would select its presidential and vice presidential candidates — and whether a Republican or a Democrat would lead it.

Between the lines: For most of 2023, the organization — which as a 501(c)(4) doesn't have to disclose its donors — shrugged off the persistent criticism that its ticket could only lead to embarrassment for the group and victory for Trump.

• But last month, No Labels asked Biden's Justice Department to open up a criminal investigation into its critics, alleging they were infringing on its right to ballot access.

Flashback: The presidential election of 1824 was determined by the House, and the Senate picked the vice presidential winner in 1837.

• Third-party bids in 1948 and 1968 didn't prevent the winners of the popular vote from securing a majority in the Electoral College.

The other side: Groups like Third Way have consistently argued that No Labels has no conceivable path to winning 270 votes in the Electoral College.

• "No Labels' fantasy electoral map defies every rule of political physics in order to claim they can win 286 electoral votes," Third Way wrote in a memo last month.
• "The data — and their own statements about triggering a contingent election — show that they are putting our democracy at risk if they go forward with this doomed plan that will re-elect Trump."

Read the full letter.