03/19/2012 02:36 pm ET Updated Mar 19, 2012

John McCain In Chicago For Mitt Romney: You 'Can't Take Illinois Primary For Granted' (VIDEO)

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Arizona Senator John McCain, in Chicago to campaign for former Massachusetts Governor Mitt Romney, made the rounds Monday morning on the city's news channels and emphasized the importance of the state's GOP primary.

"We certainly can't take Illinois for granted," McCain told NBC Chicago's Mary Ann Ahern.

"No one would have predicted this six months ago, but the fact is that what happens in Illinois will have a significant effect," he continued. "It'll either really give a sense of inevitability to the Romney campaign or then there may be a conversation about a brokered convention, which would be a disaster."

On WGN, the senator described the race between the remaining GOP presidential candidates as "a much nastier and personal campaign than we had in 2008 or the Democrats had in 2008." The negative race, he added, ultimately serves only to aid President Obama's re-election effort.

In response to Mayor Rahm Emanuel's recent criticism of Romney's refusal to stand up to conservative radio host Rush Limbaugh over his calling Georgetown Law Student Sandra Fluke a "slut" and "prostitute," McCain suggested to ABC Chicago that Emanuel "clean it up a little bit."

"I think he should show a little more respect for those of us on the other side of the aisle who also have honestly held views that may differ from his," McCain told ABC.

McCain previously described the GOP primary race as "like watching a Greek tragedy" thanks in large part to the millions of campaign dollars infused by super PACs.

The most recent polling data in Illinois, surveys conducted by the American Research Group and Public Policy Polling, show that Romney holds an edge over Santorum of between 14 and 15 percentage points. Earlier polls had shown Romney holding a narrower edge.