WASHINGTON — Claiming new momentum 48 hours before polls open across America, Republicans on Sunday criticized President Obama in a final weekend push to motivate voters as Democrats deployed their biggest stars to help preserve an endangered Senate majority.

Republican officials from Alaska to Georgia seized on the president’s low approval ratings, which have overshadowed an election season in which roughly 60 percent of eligible voters are expected to stay home.

“This is really the last chance for America to pass judgment on the Obama administration and on its policies,” Mitt Romney, his party’s 2012 presidential nominee, said in a message echoed by Republicans across the country on the weekend.

The president has avoided the nation’s most competitive contests in recent weeks, but encouraged Democrats to reject Republican cynicism during a Sunday appearance with Connecticut Gov. Dannel Malloy.

“Despite all the cynicism, America is making progress,” Obama said, imploring Democrats to vote Tuesday. “Don’t stay home. Don’t let somebody else choose your future for you.”

While the elections will determine winners in all 435 House districts and in 36 governor seats, the national focus is on the Senate, where Republicans need to net six seats to control the majority in the Congress that convenes in January. Republicans already control the House, and a Senate takeover could dramatically change Obama’s last two years in office.

Republicans appear certain of picking up at least three Senate seats – in West Virginia, Montana and South Dakota. Nine other Senate contests are considered competitive, six of them for seats in Democratic hands.

Democratic Party leaders are predicting victory despite disappointing polls.

“I’m very proud of this president,” said the head of the Democratic National Committee, Rep. Debbie Wasserman Schultz of Florida. “I think we’re going to win the Senate.”

In New Hampshire, former Secretary of State Hillary Clinton headlined a rally for Gov. Maggie Hassan and Sen. Jeanne Shaheen, a Democrat locked in a tough re-election battle against former Massachusetts Sen. Scott Brown.

Clinton, who is weighing a 2016 presidential bid, charged that Republicans are running a campaign of fear.

“Fear is the last resort for those who have run out of ideas and hope,” she said in her first appearance in New Hampshire since October 2008.

In Georgia, where Democrats see an opportunity to gain a seat in traditionally Republican territory, Republican David Perdue repeatedly called Democrat Michelle Nunn a “rubber stamp” for Obama during a Sunday debate.

Nunn mockingly told Perdue he sounds like he’s “running against the president.”

“You’re running against me, David,” Nunn said.

In Colorado, Democratic Sen. Mark Udall’s best hope remains a robust ground game. He made four stops at campaign offices to fire up door-knockers, reminding them, in classic Colorado fashion, to knock on doors before the Broncos football game.

“We’re going to bring this one home in the next 72 hours,” Udall said in the suburb of Centennial. He told volunteers to disregard polls that find him narrowly trailing Republican Rep. Cory Gardner.

While the campaigns’ costly voter turnout operations were in full swing, large percentages of younger voters and minorities – groups that typically support Democrats – are expected to sit out the elections altogether.

None of the last four midterm elections drew more than 38 percent of the voting-age population. Early voting has been strong this year, however.

At least 16.7 million people have voted so far across 31 states, according to early voting data monitored by The Associated Press. Arkansas, Florida, Georgia, Iowa, Louisiana, Maryland, Montana, North Carolina, Wisconsin and Utah already surpassed their 2010 advance totals; party registration is divided about equally among those who have already cast ballots.

Senate Republican Leader Mitch McConnell cited encouraging polls as he campaigned across Kentucky, where he’s trying to hold off a challenge from Democrat Alison Lundergan Grimes.

“We expect to win,” McConnell said after riding in a Veterans Day parade.