At a rally in Doswell, Virginia, Romney criticized Obama's comment that he would like to consolidate government agencies that deal with business issues in a new department under a secretary of business.
"I don't think adding a new chair to his Cabinet will help add millions of jobs on Main Street," Romney said.
Jobs will again be the focus of fierce debate on Friday when the government releases the unemployment figures for October. Any big change from the 7.8 percent number in September could potentially sway voters.
Obama and Romney had put campaigning on hold for several days as the historic storm Sandy pounded the eastern seaboard, leaving a trail of destruction and forcing Obama to turn his attention to storm relief.
That pause produced some unexpected political benefits for Obama, who won warm praise from Republican Governor Chris Christie of New Jersey, a Romney supporter, and he spent days directing federal relief efforts in a show of presidential leadership that largely sidelined Romney.
New York's Bloomberg - a Republican-turned-independent who did not back a candidate in 2008 - endorsed Obama and cited the Democrat's record on climate change, an issue that has gained more attention since the storm.
Bloomberg said Obama had taken significant steps to reduce carbon consumption, while Romney had backtracked on earlier positions he took as governor of Massachusetts to battle climate change. Obama said he was "honored" by the backing of Bloomberg, who flirted with White House runs in the past.
On their first day back on the trail, both Obama and Romney returned to political attacks but struck a slightly more positive tone than usual in trying to woo undecided voters and push their own supporters to vote.