The Michigan GOP primary has shaped up to be a significant battle just one week before Super Tuesday.

The contest could prove to be an outstanding upset for Rick Santorum, who had been gaining support amongst conservatives, but lost ground in the polls this past week. However, prior to the primary, even the latest polls had Santorum in a dead heat with Mitt Romney.

(UPDATE: Romney wins Michigan and Arizona. Scroll down for full maps and results.)

Michigan could be a good indicator of how the Republican candidates would fare in the Midwest in the general election, according to the Boston Globe, as the ability to woo blue-collar voters in swing states will be tested. A loss for Romney, who was born in Detroit, could be a big blow to his chances for winning the GOP nomination and would raise questions about his ability to defeat President Barack Obama in November.

Arizona, which Romney won, held its primary simultaneously with Michigan. For the GOP, Arizona is an all-or-nothing battle, with 29 delegates up for grabs. Grand Canyon State Gov. Jan Brewer (R) endorsed Romney this past weekend.

For full coverage of the Arizona and Michigan primaries, be sure to check out our liveblog. You can also see real-time results of the contests as they come in, district-by-district, below.

Map credits: Jay Boice, Aaron Bycoffe, Daniel Lee, Christian Rocha and Andrei Scheinkman. Data provided by the Associated Press.