All planes have been grounded at the Des Moines airport, causing havoc on the campaign trail.

(CNN) –- Snow and ice shut down campaign season in Iowa Tuesday, as politics took a back seat to safety concerns and travel headaches.

On the Democratic side, former President Bill Clinton has canceled planned stops on behalf of his wife, New York Sen. Hillary Clinton. The events were to take him to In West Branch, Wapello, and Burlington, Iowa.

John Edwards canceled his first event of the day in Clinton, though the campaign hoped the former North Carolina senator would be able to make it to planned evening in events the eastern part of the state.

As for Republicans, former Arkansas Gov. Mike Huckabee – the leader in recent Hawkeye State polls – has canceled two appearances. But the weather couldn’t stop the latest round of an increasingly bitter between Huckabee and former Massachusetts Gov. Mitt Romney over immigration.

On a day when both campaigns are on the air with new ads attacking his past stands on immigration policy, Huckabee went ahead with a Council Bluffs event where he received an endorsement from Jim Gilchrist, the founder of the anti-immigration group Minuteman Project.

Romney is planning to go forward with a midday event in Des Moines, but his wife Ann has canceled her campaign appearances.

Texas Rep. Ron Paul has several stops in Iowa planned starting Tuesday afternoon. His campaign said the events will go forward as scheduled, though they are continuing to assess the travel situation.

– CNN Political Desk Managing Editor Steve Brusk