Updated: 5:47 p.m.

Obama will use a speech at an Associated Press luncheon to press the “Buffett Rule,” which would ensure that the wealthy pay comparable tax rates to those of the middle and lower classes, senior administration officials said today.

The Senate is set to consider the Buffett Rule the week of April 16, when it returns from its spring recess.

The officials also said the president would use the speech to criticize the House-passed Republican fiscal 2013 budget, which was adopted largely along party lines last week in that chamber.

Democrats contend that both the Buffett Rule and the GOP budget underscore the theme of income inequality, an issue that they believe will resonate with middle-class voters.

A senior GOP aide questioned Democrats’ decision to move the Buffett Rule while the chamber has done nothing to address rising gas prices.

“Who thinks the Senate has finished its work on gas prices or jobs?,” the aide asked. “It’s like they don’t even care about either topic. If one job was created every time Democrats tried to change the subject, America would be well on our way to full employment.”

Obama discussed the issue in his weekly radio address Saturday.

“When it comes to paying down the deficit and investing in our future, should we ask middle-class Americans to pay even more at a time when their budgets are already stretched to the breaking point?” Obama asked. “Or should we ask some of the wealthiest Americans to pay their fair share?”

The Buffett Rule is named for billionaire investor Warren Buffett, who has criticized the lower tax rates paid on investments compared with the tax rate paid on wages and other earned income.

The Senate is set to take a procedural vote when it returns on whether to take up a bill, introduced by Sen. Sheldon Whitehouse (D-R.I.) in February, that would ensure that individuals making more than $1 million a year pay at least a 30 percent tax rate to put them on par with the percentage paid by most middle-income taxpayers.

“If they vote to keep giving tax breaks to people like me — tax breaks our country can’t afford — then they’re going to have to explain to you where that money comes from,” Obama said in his Saturday address.

Senate Republicans are likely to deny the Democrats the votes needed to cut off debate on the motion to proceed to the bill, which would result in killing the measure. Sixty votes are needed and Democrats control only 53 votes.

Republicans argue the measure would be a jobs killer because it would raise taxes on small-business owners who tend to file their businesses taxes as part of their individual income tax.

But the Senate GOP might also take up Democrats’ invitation to debate the issue with an eye to vote it down later in the week. This would follow a similar pattern as last week’s debate on repealing oil and gas subsidies.

Despite admonitions from Senate Democrats and Obama, the Senate voted 51-47, failing to reach the 60 votes needed to cut off debate on the oil and gas tax break repeal measure.

The 47 votes against the bill included Democratic Sens. Mark Begich (Alaska), Mary Landrieu (La.) Ben Nelson (Neb.) and Jim Webb (Va.) voting with Republicans against cutting off debate on the bill. GOP Maine Sens. Susan Collins and Olympia Snowe joined with Democrats.

With regard to the House GOP budget plan, Obama is expected to continue to highlight the differences between it and his approach.

Democrats have criticized the House budget, sponsored by Budget Chairman Paul Ryan (R-Wis.), for giving tax breaks to the wealthy and cutting discretionary spending and revamping Medicare, which Democrats argue would result in higher health care costs to seniors.

Ryan’s proposal also lowers discretionary spending from $1.047 trillion to $1.028 trillion for fiscal 2013, which Democrats argue breaks an agreement Congress and the administration agreed to and enacted into law: the Budget Control Act.

Also, on Friday the administration will host the White House Forum on Women in the Economy, according to a White House official. Obama is scheduled to address the gathering.

As part of the meeting, the White House will release a report on women and the economy that examines the ways in which the administration has worked to ensure women’s economic security and create jobs for women through all stages of life, the official said.

White House Senior Adviser Valerie Jarrett, Health and Human Services Secretary Kathleen Sebelius, Secretary of Labor Hilda Solis and Attorney General Eric Holder are expected to participate.