By Larry Kane

PHILADELPHIA (CBS) – New Jersey Governor Chris Christie has accelerated his national media exposure, this week. With Mitt Romney struggling ahead of tomorrow’s primary in Michigan, some political insiders are not happy about it.

Tomorrow, Mitt Romney faces the most critical test of his frustrating run for president: Michigan. But, in the days leading up to it, a man who has endorsed him, Chris Christie, is campaigning alone on national television.

kane larry tight Analysis: Romney Backers Wary About Christie’s Increased Exposure

(KYW's Larry Kane.)

His appearances, almost every other day, including one yesterday on CBS’ Face the Nation, mentioned Romney. Noteworthy are his comments that there could be a brokered GOP convention. Those comments do not appear to be helpful to Romney.

WATCH: Chris Christie Appears On CBS’ Face The Nation

Christie is a master of media (mostly national) and inserting himself into the national dialogue in Romney’s most important week has upset some Romney insiders in this area.

The question is: What’s his game? What’s his motive?

He says now that he would consider a VP run, but if the nominee were Romney, would he go for Christie? And if Romney loses the nomination, is Christie’s new national media blitz — despite his own denials — a sign that he’s ready if called for the number one spot?

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