Obama, in an address from the White House later Monday, will call on Congress to pass a one-year extension of tax cuts for households making less than $250,000 a year, said senior campaign adviser Robert Gibbs.

The president’s appeal to middle-class voters is aimed at drawing a contrast with Romney and congressional Republicans. The House GOP is expected to make its own push this month for an extension of all the Bush-era tax cuts due to expire at the end of the year, including reductions on wealthier income earners.

Obama opposes extending the tax cuts for Americans with higher incomes, while Romney has said he supports extending the expiring cuts for all income earners.

The president’s announcement Monday comes as Democrats embark on a coordinated attack on Romney, intensifying calls for him to explain offshore bank accounts and release several years of tax returns.

The strategy is aimed at portraying Romney, whose personal wealth could exceed $250 million, as disconnected from middle-class voters.

“We have to continue to grow our economy. We have to grow it from the middle class out,” Gibbs said Monday in an interview on NBC’s “Today” show. “But for millionaires and billionaires, they don’t need a tax cut,” he added.

Gibbs said, “We’re going to have to make some tough choices in this country. We can’t continue to spend the kind of money that was spent in the last decade.”

The Romney campaign had no immediate comment on Obama’s tax proposal.

Romney aides have called Democratic attacks on the presumptive GOP nominee’s wealth an “unfounded character assault.”

Romney hasn’t shirked from his wealth in the face of renewed Democratic criticism. He held a $50,000 per person fundraisers Sunday in the Hamptons, New York’s exclusive string of waterfront communities on Long Island’s South Shore.

Romney aides also announced that the campaign and the Republican National Committee raised a combined $106 million in June, the former Massachusetts governor’s biggest monthly haul so far. The Obama campaign has not yet announced its June fundraising total.

Obama was to make his case for the middle class tax cut extension during an event in the White House East Room later Monday. He was expected to be joined at the event by several people the White House says would benefit from the extension.

The president was also to continue the tax debate Tuesday during a campaign trip to Iowa. His re-election team was also promoting the president’s tax policy at a series of events this week in battleground states, including New Hampshire, Colorado and Nevada.

The president’s shift to the tax debate follows Friday’s lackluster jobs report showing the nation’s unemployment rate stuck at 8.2 percent.

The Bush-era tax cuts are due to expire at the end of the year unless Congress votes to extend them. Economists worry that across-the-board tax increases, along with automatic spending cuts also scheduled to take hold at year’s end, could be a blow to the shaky U.S. economy.