The president's campaign, which also seems convinced Obama will face Romney in the November election, is running television ads that try to link the former Massachusetts governor to big oil companies as high gas prices threaten to influence already stressed voters.
"Mitt Romney's stood with Big Oil — for their tax breaks, attacking higher mileage standards and renewable energy sources," an ad says. It's a response to an ad from the American Energy Alliance blaming Obama for rising gas prices.
With Republican primaries Tuesday in Wisconsin, Maryland and Washington, D.C., Romney is set to hold one campaign event before an election night party in Wisconsin. He spent the weekend campaigning there, working to win yet another big industrial state that chief rival Rick Santorum was counting on to keep his fading candidacy alive.
"The right thing for us, I think, is to get a nominee as soon as we can and be able to focus on Barack Obama," Romney told Fox News in an interview.
Romney has ignored the conservative Santorum the past few days as he has focused on Obama, telling supporters that the president "takes his political inspiration from the capitals of Europe." The often used Republican line of attack is meant to imply an opponent is elitist and not in touch with the American mainstream.
Obama, meanwhile, was to issue a broad attack on Republicans later Tuesday, criticizing their budget plan that has already passed in the House of Representatives and has Romney's backing.
In a speech to newspaper executives, Obama will sharply criticize the $3.5 trillion budget proposal pushed by Rep. Paul Ryan. It has faced fierce resistance from Democrats, who say it would gut Medicare — the government health insurance program for older Americans — while cutting taxes for the wealthy and leading to deep cuts in crucial programs such as aid to college students and highway and rail projects.
"It's a Trojan horse. Disguised as deficit reduction plan, it's really an attempt to impose a radical vision on our country," Obama said in excerpts of his speech. "It's nothing but thinly veiled social Darwinism." Romney has 572 Republican National Convention delegates, half of the 1,144 needed to win the Republican nomination, and is on a pace to clinch it by the end of the primary season in June. Santorum has 272 delegates. Newt Gingrich, the former speaker of the House of Representatives, has 135 and Texas Rep. Ron Paul 51.
There were 95 delegates at stake Tuesday, including 42 in Wisconsin, the only one of the three contests that Santorum seriously contested. Romney is expected to do well in Maryland and in the US capital, where Santorum's name doesn't appear on the ballot.
Romney's campaign is running far behind the president in fundraising, however, as he's been unable to raise general election money because of the drawn-out primary contest.
At the end of February, Obama reported $84.7 million in his campaign account compared with Romney's $7.3 million. Obama has more than 530 paid staff compared with roughly 100 for Romney.
But Romney has far out spent his Republican rivals.
Santorum, also campaigning in Wisconsin on Monday, said Romney has essentially bought his success by outspending the competition.