With one last week to go before Election Day, Minnesotans can expect their front doorsteps and telephones to become battlefields in the presidential campaign.

Local strategists for Democrat Barack Obama and Republican John McCain unveiled their plans for the final push of the longest campaign, with both pledging that theirs would be the biggest get-out-the-vote effort in the state's history.

Both will concentrate their volunteers' firepower on still-undecided voters and those whose support of their candidate remains soft, campaign managers said.

"We've always said Minnesota is a must-win state and we're running it in a must-win way," said Jeff Blodgett, Obama's chief strategist in the state.

Responded his counterpart at the McCain campaign, Ben Golnik: "Our get-out-the-vote operation is efficient, battle-tested and a proven turnout method."

About 20,000 Obama volunteers are operating out of 37 offices statewide, planning to make 1 million voter contacts by next Tuesday, Blodgett said.

About a half-million new or what he called "irregular" voters will have been contacted four times each during the campaign by then, he said.

Golnik said thousands of GOP volunteers will contact tens of thousands of voters; "we don't get into specific numbers," he said. "We know the Obama campaign has more paid staff and offices."

The McCain campaign is working out of 15 field offices statewide.

Both campaigns will have volunteers working straight through next Tuesday.

Recent polls in the state show Obama with a lead over McCain.