Presidential candidates aren’t rushing to sign up for the bipartisan presidential forum Mayor de Blasio is planning in Iowa.

Only two contenders — Vermont Sen. Bernie Sanders and former Maryland Gov. Martin O’Malley — have expressed interest in the Dec. 6 event. Hillary Rodham Clinton, the Democratic front-runner, hasn’t said if she’ll attend and her campaign keeps ignoring questions about whether she’ll have a role.

Donald Trump, the Republican front-runner, says he won’t there.

A rep for Carly Fiorina said she had not even been invited.

“Is this is a joke?” asked Doug Watts, a rep for candidate Ben Carson.

De Blasio asked for RSVPs by Tuesday.