Gov. Mitt Romney, a possible McCain running mate, will be the star guest today when Sen. John McCain’s campaign officially opens its regional office in Farmington Hills.

Continued – The office, which has been operating since late June, anchors Wisconsin, Indiana and Michigan. Its location in Oakland County puts it in the heart of Romney’s support base.

Romney, McCain’s former rival for the Republican presidential nomination, is now considered a top potential pick to be the Arizona senator’s running mate, in part due to his popularity in Michigan. Romney defeated McCain in the Michigan primary in January.

Michigan, with its 17 Electoral College votes, is viewed as a key battleground state in the November election between McCain and Sen. Barack Obama. The state last supported a Republican for president in 1992, when a majority of voters pulled the lever for George H.W. Bush. However McCain’s popularity here — he won the state’s primary against President Bush in 2000 — combined with Romney’s organization, is keeping Michigan in play. He’s running broadcast ads in the state, as is Obama. Romney is well known in Michigan as a native son and the son of a former governor, and some analyts have speculated that he might be able to help turn the blue state red.

McCain held a town-hall event for small business owners in Belleville on Thursday, his first public appearance in the state since early May.

The campaign office is located at 31440 Northwestern Highway.