Texas Gov. Rick Perry is the latest presidential candidate to reject a debate moderated by real-estate mogul and reality-TV star Donald Trump .

The Dec. 27 forum is being hosted by the conservative Web site Newsmax and broadcast on Ion Television. Republican leaders have been urging candidates to avoid the event, warming that it could easily devolve into a circus-like atmosphere.

Perry’s campaign said in a statement that the decision was motivated by timing, not any disputes with Trump.

“Gov. Perry has talked to Donald Trump in recent days and respects him and the folks at Newsmax very much,” Perry communications director Ray Sullivan said in a statement. “Traditional retail campaigning in the days and weeks leading up to the Iowa caucus is the Perry campaign’s top priority.”

Former Massachusetts governor Mitt Romney and former Utah governor Jon Huntsman have already declined the invitation. Rep. Michele Bachmann (R-Minn.) is undecided. Former House speaker Newt Gingrich and former Pennsylvania senator Rick Santorum (Pa.) are planning to attend.

Gingrich suggested on Fox News earlier this week that other candidates’ unwillingness to attend was a sign of weakness: “You want me to believe you can debate Barack Obama, but you won’t debate Donald Trump?”

But veteran Republicans, including strategist Karl Rove and Republican National Committee Chairman Reince Priebus, have spoken out against the debate. The general lack of interest suggests that Trump has pushed the limits of his influence on the GOP.