AP: Mitt Romney wins Arizona, Michigan Republican presidential primaries

WASHINGTON — Mitt Romney has narrowly won the Michigan Republican presidential primary.

The former Massachusetts governor defeated Rick Santorum, who had waged a hard-fought battle for the state.

Michigan is critical for Romney because it is the first of the nation’s industrial battleground states to vote in the GOP nominating race — and it is also his home state.

Earlier Tuesday night, Romney easily won the Arizona GOP primary.