Updated

Democrats going up the chain all the way to Vice President Biden tried feverishly on Sunday to reverse Robert Gibbs' prediction that Republicans could seize the House in November, as GOP lawmakers claimed Washington indeed was on the verge of a power shift.

The White House press secretary earned a rebuke from House Speaker Nancy Pelosi last week when he claimed her majority was in peril. Pelosi's deputies on Sunday sought to put that notion to rest as Biden made a confident prediction about his party's chances in November. He said voters don't yet grasp the benefits of Democrat-passed policies but that they will begin to crystallize in time for the midterm elections.

"I think we're going to shock the heck out of everybody," Biden said. "We're going to win the House and we're also going to win the Senate. We're not going to lose either one of those bodies."

Speaking on ABC's "This Week," Biden said Democratic losses in the fall would not be so severe. "To paraphrase Mark Twain, I think the reports of our demise are premature," he said.

Democrats like Gibbs have reason to be concerned. The economy is still on shaky ground, and poll after poll shows President Obama's approval ratings down and voters increasingly looking for a Republican alternative in Congress come November.

An ABC/Washington Post poll last week showed registered voters would rather see Republicans take control of Congress by an 8-point margin. A Fox News/Opinion Dynamics poll released Friday showed 33 percent of registered voters say their 2010 vote for Congress will express support for Obama - with 41 percent saying their vote will reflect opposition to Obama.

A key House Republican, speaking on "Fox News Sunday," countered Biden's fall prediction.

"The American people are looking for men and women who are committed to those timeless American principles to get this economy moving against -- fiscal discipline in Washington, D.C., fast-acting tax relief for working families," said Rep. Mike Pence, R-Ind.

Pence said any economic growth has been occurring "in spite" of Democrats' policies, not because of them, and accused the administration of showing an "absence of leadership."

"I'm optimistic," Pence said. "Maybe not as optimistic as Robert Gibbs, but I like our chances."

Biden said all Democrats need is time to change voter attitudes. He said the skepticism exists -- over legislation like the stimulus package, the health care bill and the financial overhaul package -- because the public just doesn't understand the "details" of what's in those laws.

"This is July -- election's not until November, and I think we're going to have to affirmatively make our case," Biden said. "I think we can make it."

Biden and other Democrats said Sunday that voters are sure to realize that Republicans stand for a return to failed policies.

Rep. Chris Van Hollen, D-Md., chairman of the Democratic Congressional Campaign Committee, said on NBC's "Meet the Press" that Minority Leader John Boehner's pledge to repeal the financial overhaul bill makes the alternative clear.

"We're confident we're going to retain a majority in the House," Van Hollen said.

House Democratic Whip James Clyburn, D-S.C., said on "Fox News Sunday" that despite the "tough climate," Democrats would have a "strong showing" in November.

But Republicans had predictions of their own. Rep. Pete Sessions, R-Texas, chairman of the National Republican Congressional Committee said his party would gain just more than 40 House seats to seize control of the chamber in November.

Sessions' campaign counterpart on the Senate side Sen. John Cornyn, R-Texas, said Americans want "checks and balances" in Washington to counter the "unprecedented spending binge."

"They see Republicans as the best bet to provide those checks and balances," he said.

Sessions and Cornyn spoke on "Meet the Press."