Republican U.S. presidential candidate Mitt Romney and his new running mate are casting themselves as the duo to bring back America's economy.

Romney and Representative Paul Ryan moved through North Carolina on Sunday as part of a multi-state tour. The state is considered critical in the race for the White House.

Romney is hoping Ryan's work in Congress to cut spending and create smaller government will help energize the Republican Party's conservative base.

The pair launched their four-day campaign bus tour on Saturday, immediately after Romney announced the 42-year-old congressman as his vice presidential pick.

President Barack Obama's campaign blasted the pick, saying Ryan put forth a budget that would cut taxes for the wealthy and put more burdens on the middle class and seniors.

Romney, the presumptive Republican nominee, will face President Obama, a Democrat, in the November 6 election.