Jesus “Chuy” Garcia would appear to be the kind of candidate U.S. President Barack Obama would happily support for Chicago mayor. Garcia is a Mexican immigrant from the progressive wing of the Democratic Party, and is a Chicago community organizer, as Obama was. But Garcia is challenging incumbent Mayor Rahm Emanuel, Obama’s former chief of staff. Political observers say the president had no choice but to back Emanuel’s re-election bid.

“Anyone who knows anything about Obama’s earlier career in Chicago politics knows that were he not president, he would be supporting Chuy,” said Jeremy Mayer, an associate professor at the School of Policy, Government and International Affairs at George Mason University in Arlington, Virginia. “If you look at Obama’s record as a progressive, he was not part of the Rahm Emanuel wing of the Democratic Party. If you look at the kind of profile Obama had as a state legislator in the Chicago universe, he was far to the left of where Rahm Emanuel is. He was not someone who is tight with big money the way Rahm Emanuel and Wall Street got along.”

But Obama was bound by allegiance to back Emanuel for a second term: “A president who doesn’t do whatever he can, who doesn’t help whoever’s loyal to him is breaking a rule in American politics,” Mayer said.

On Tuesday, Garcia -- a Cook County commissioner, former Chicago alderman and former state legislator -- rocked the local political establishment by forcing Emanuel into a runoff after the incumbent couldn’t cross the 50 percent threshold to win re-election in a five-way race. Emanuel got 45 percent of the vote and Garcia got 34 percent, making this year’s contest the first time a Chicago mayoral election heads to a runoff, which will take place in April.

Garcia tapped into anti-incumbent sentiment over rising crime in Chicago and Emanuel’s controversial decision to close 50 of the city’s schools that he deemed either underperforming or underutilized. That put Emanuel at odds with Chicago’s powerful teachers union, which endorsed Garcia.

Matthew Dallek, an assistant professor of political management at George Washington University in Washington, said it was striking that Obama’s support wasn’t enough for Emanuel to avert a runoff. “There is a little bit of awkwardness in the sense that he came out, he did an event with Rahm Emanuel, he visited an Emanuel campaign office -- he clearly endorsed him very strongly and tried to get him over the hump,” he said. “If the fact that his chosen candidate and former chief of staff did not get over 50 percent, it doesn’t look great, certainly. At the end of the day, if Emanuel wins in the runoff, then I think it just becomes much less of an issue."

When asked whether he believed Obama might have preferred to endorse Garcia, U.S. Rep. Luis Gutierrez, a Democrat and the first Latino in the Midwest elected to serve in Congress, rejected the implication that Obama should base his choice on ethnicity or identity. “No one should vote for a candidate on the basis of their sexual orientation, their race, their nationality,” Gutierrez said. “I don’t think anybody would be asking a question if it were: ‘Should we vote for a white candidate because they’re white? Should we vote for a black candidate because they’re black?’ I mean, the very question I think is very, very dangerous. We should vote for people based on the public policies they propose and the future agenda they presented.” Gutierrez, a vocal immigrants-rights advocate, has already endorsed Emanuel.

While Chicago is the base of Obama’s political support, analysts say the president’s sway in the mayoral race is limited because voters are deciding it on local issues. Also, Obama’s support for Emanuel was taken as a given. But should Garcia prevail -- and most political observers don’t expect him to -- it could again lead to questions about the efficacy of Obama as a campaigner, Dallek said. “If Emanuel’s opponent were somehow were to win,” he said, “it gives the media the ability to say, ‘How come one of Obama’s top people … and a very savvy political leader in his own right, how come he can’t win re-election?’”

IBTimes senior political reporter Ginger Gibson contributed reporting from Washington.