MILWAUKEE (AP) — Hoping to help Democrats score a big coup on what could be an otherwise dismal Election Day, President Barack Obama campaigned for the defeat of Wisconsin's high-profile Republican governor, long seen as a potential 2016 presidential candidate.

With election day just a week away, Obama arrived in Wisconsin Tuesday to attend a rally for Mary Burke, the Democratic challenger trying to oust Republican Gov. Scott Walker, whose anti-union and budget cutting policies have made him a hero to many on the right.

While Obama has largely stayed away from campaigning in congressional races, Democrats are hoping high turnout among die-hard supporters of the president will put them over the top in hard-fought races for governor.

Polls show the Wisconsin race is deadlocked between Walker and Burke, with very few voters undecided. Obama won Wisconsin in the 2008 and 2012 presidential elections.

At a packed gymnasium in Milwaukee, Obama held up Burke as a skilled businesswoman who will fight for the type of middle-class opportunity that made his own success possible. Although Democrats hoped Obama's appearance with Burke would help put her over the top in next week's tight race, Republicans confidently predicted Obama would have just the opposite effect.

Riffing on health care, the minimum wage and women's issues, Obama steered clear of referring directly to Walker, instead lumping him together with a Republican Party he accused of pushing antiquated and failed policies — such as opposition to fair pay for women legislation backed by Democrats.

"We need to strengthen the middle class for the 21st century. That means we need leaders from the 21st century who actually believe women should get paid the same as men," Obama said to cheers and laughter.

Obama has been a rare sight on the campaign trail this year — he made his first appearances just over a week ago — in large part due to low approval ratings that make him a potential liability for Democrats.

Even the setting for Obama's rally — a high school in a mostly black part of Milwaukee — served as a reminder of how limited Obama's appeal has become, both in geography and demographics. Only seven voters in the ward where Obama held his rally voted for someone other than Obama in 2012, records show.

Still, the White House hopes Obama can help turn out high numbers of voters who backed his own presidential campaigns — chief among them African-Americans, Hispanics, young people and women.

"The country as a whole is doing better. Wisconsin's not doing so good," Obama said. "Over the next week, you have a chance to change that. You have a chance to choose a governor who doesn't put political ideology first."

The rally before 3,500 people, including former "West Wing" actor Bradley Whitford, opened a week of last-minute campaigning by Obama. He plans to travel to Michigan, Maine, Rhode Island, Connecticut and Pennsylvania — all states where Democrats are optimistic about the governor's races, in contrast to the party's gloomy expectations for the Senate. Obama only has plans to campaign with one Democratic Senate candidate — Michigan Rep. Gary Peters.

But even in Wisconsin, Obama's ability to fire up Democrats without driving up Republican turnout was in question. Joe Fadness, head of the Republican Party of Wisconsin, said Obama's appearance with Burke would remind voters that Obama's economic policies are on the ballot on Election Day.

"Wisconsin can't afford a governor who will walk lock-step with President Obama and his failed policies that have hurt our country and would take Wisconsin backward," Fadness said.

But former President Bill Clinton has proven to be a leading surrogate for embattled Democratic candidates in contests that may determine whether the party can keep control of the Senate.

On Tuesday, he campaigned for the second straight day in Colorado where polls show Democratic Sen. Mark Udall narrowly trailing Republican Rep. Cory Gardner. Hovering in the backdrop of the former president's intense stumping in Colorado is the prospect of his wife's upcoming presidential campaign, which will inevitably contend in this swing state.

Republicans are expected to retain control of the House of Representatives and need only six seats to gain control of the Senate in the Nov. 4 elections. If Republicans regain a Senate majority, it would make it difficult for Obama to achieve many of his legislative goals during the remaining two years of his term, from raising the minimum wage to immigration reform legislation.

Senate Democrats unleashed a late-campaign round of attack ads Monday accusing Republicans in key races of harboring plans to cut national Social Security pension benefits and the Medicare health program for the elderly. The ads appear aimed at older voters, who cast ballots in relatively large numbers in midterm elections and have tended to support Republicans in recent years.

Early voting is already under way in many cities. Nationally, the parties are very close in early voting. Roughly 8.6 million ballots have been cast so far in 27 states. About 41 percent have been for Republicans and 40 percent for Democrats. In states with tight Senate races, Democrats are far ahead in North Carolina and Louisiana, while Republicans currently lead in Colorado.