Republican nominee Mitt Romney steps off the campaign trail for much of this week as he prepares for next month's crucial debates against Barack Obama, whose Democrats are gathering to re-nominate the president.

Aides said the newly crowned Republican flagbearer will spend most of Tuesday through Thursday in the northeastern state of Vermont, adjacent to his home state of Massachusetts where he once served as governor.

Romney's focus will be on intensive preparations for the three nationally televised face-offs he will have with Obama, beginning October 3 in Denver, Colorado with a debate that focuses on domestic policy.

It's a different tack than the one used by Obama, who campaigned vigorously last week during theRepublican National Convention held in Tampa.

Romney campaign officials told reporters this weekend that Republican Senator Rob Portman of Ohio will play Obama -- reprising a role he took during debate rehearsals in 2008 -- in this week's sessions, which take place at the Reading, Vermont home of Romney's former lieutenant governor Kerry Healey.

The nominee will leave this week's political counterattacks to surrogates and his running mate Paul Ryan, who campaigns Tuesday in Ohio and Iowa, two key battleground states in the November 6 election.

On Monday Ryan bracketed the Democrats in North Carolina, the state where the Democratic National Convention is being held this week in Charlotte.

He and Republicans were taking a strategy out of the playbook of revered conservative president Ronald Reagan to ask whether US voters were better off now than they were four years ago.

"The president can say a lot of things, and he will, but he can't tell you that you're better off," Ryan told a crowd Monday at East Carolina University in Greenville, about 230 miles (370 kilometers) from Charlotte, as he offered a scathing comparison between Obama and a one-term 1970s Democrat.

"Simply put, the Jimmy Carter years look like the good old days compared to where we are right now," he said.