MINNEAPOLIS — Mitt Romney is suddenly plunging into traditionally Democratic-leaning Minnesota and Pennsylvania, and his GOP allies are trying to put Michigan into play. It’s forcing President Barack Obama to defend his own turf – he’s pouring money into television ads in the states and dispatching top backers – in the campaign’s final week.

The question is: Why this Republican move?

GOP efforts in the trio of Rust Belt states could indicate that Romney is desperately searching for a last-minute path to the needed 270 Electoral College votes – without all-important Ohio.

Or perhaps the Republican simply has money to burn. Use it now or never.

This late-game expansion of a campaign playing field that, until now, had focused on just nine states was taking place exactly a week from Election Day.

Of the nine states where the two men have spent more than $1 billion in advertising since June, Romney is in the strongest position in North Carolina.

But public and internal campaign polls show he’s locked in stubbornly tight battles in Colorado, Florida, New Hampshire, Nevada and Virginia and is fighting to overtake Obama’s advantage in crucial Ohio as well as Iowa and Wisconsin.