Obama: Voters shouldn't trust Romney

• Obama opens two-day blitz of battleground states
• Says voters shouldn't trust Romney
• Appears with Jay Leno on Wednesday night

President Obama opened a two-day, eight-state blitz of battleground states Wednesday by saying voters should not trust Republican rival Mitt Romney.

"There's no more serious issue in a presidential campaign than trust," Obama told a fairground rally in Davenport, Iowa, one of a handful of states that will decide his race with Romney.

The president said Romney has changed his position on too many issues and that his tax cut proposal can't possibly reduce the federal debt without major program cuts or tax hikes on the middle class. "Governor Romney's jobs plan doesn't really create jobs," Obama said.

Obama said his plan included building up the U.S. manufacturing base, reducing dependence on foreign oil, improving education, cutting budget deficits and building more roads, bridges and schools.

"I haven't finished all the work we set out to do in 2008 just yet, but I have fought for you every single day that I've held this office," Obama said.

Romney aides said the president is the one who shouldn't be trusted, given the state of the economy.

"President Obama proved once again today that his campaign is getting smaller and smaller as Election Day approaches," said Romney spokesman Ryan Williams. "Another four years of President Obama's policies will mean lower incomes, higher taxes, and more debt."

Williams also dismissed Obama's second-term agenda, saying that "a glossy brochure full of the same policies that haven't worked over the last four years is no substitute for a real agenda that will help grow the middle class and restore America's strength."

In continuing his "America Forward!" tour, Obama spoke later in Denver, and was scheduled for a late night appearance in Las Vegas.

In between those stops, he travels to Los Angeles for a taped appearance on The Tonight Show with Jay Leno.

After the Las Vegas rally late Wednesday night, Obama flies to the Tampa area for a rally on Thursday morning; the president will sleep aboard Air Force One.

"We're going to pull an all-nighter!" Obama joked in Denver. "No sleep! Quite a bit of coffee!"

In addition to Florida, Obama will campaign Thursday in Virginia and Ohio. He also takes a side trip to his hometown of Chicago to cast his absentee vote.