New York Mayor Michael Bloomberg says he can run on US presidential ticket with Arnold Schwarzenegger

New York Mayor Michael Bloomberg talked playfully this week about running on a U.S. presidential ticket with Arnold Schwarzenegger, but the legal obstacles that prevent the Austrian-born California governor from serving as president also would block him from the nation's No. 2 job, legal scholars say.

However, those obstacles could be challenged, some added.

As a foreign-born citizen, Schwarzenegger is prohibited by the U.S. Constitution from holding the presidency. And the 12th Amendment, ratified in 1804, bans the native of Austria and other naturalized Americans from serving as vice president.

Those prohibitions might be open to legal challenge, and it is not clear what would happen if Schwarzenegger or another foreign-born candidate decided to run, several legal scholars said.

"The law is very clear, but it's not 100 percent clear that the courts would enforce that law rather than leave it to the political process," said Columbia University Law School professor Michael Dorf, an expert in constitutional law.

Yale Law School professor Jack Balkin said the "terrible rule" should be dropped.

Aides to Schwarzenegger, who became a citizen in 1983, said the issue is not commanding his attention. Political advisers, however, have examined it and concluded he is ineligible for either office.

With America growing increasingly diverse, Schwarzenegger's election as governor in 2003 helped bring about a fresh examination of the qualifications to hold the presidency and vice presidency. A joint resolution introduced in the U.S. Congress in 2004 would have extended eligibility for the presidency to immigrants who have held U.S. citizenship for at least 20 years.

This week, Bloomberg talked playfully about forming a presidential ticket Schwarzenegger.

"There would be a fight to see who would be the presidential candidate and who would be the vice presidential candidate," Bloomberg quipped. "He would want to arm wrestle for the top spot; I would want to check the Constitution."