WASHINGTON  President Obama on Wednesday will make clear that he opposes any compromise that would extend the Bush-era tax cuts for the wealthy beyond this year, officials said, adding a populist twist to an election-season economic package that is otherwise designed to entice support from big businesses and their Republican allies.

Mr. Obama’s opposition to allowing the high-end tax cuts to remain in place for even another year or two would be the signal many Congressional Democrats have been awaiting as they prepare for a showdown with Republicans on the issue and ends speculation that the White House might be open to an extension. Democrats say only the president can rally wavering lawmakers who, amid the party’s weakened poll numbers, feel increasingly vulnerable to Republican attacks if they let the top rates lapse at the end of this year as scheduled.

It is not clear that Mr. Obama can prevail given his own diminished popularity, the tepid economic recovery and the divisions within his party. But by proposing to extend the rates for the 98 percent of households with income below $250,000 for couples and $200,000 for individuals  and insisting that federal income tax rates in 2011 go back to their pre-2001 levels for income above those cutoffs  he intends to cast the issue as a choice between supporting the middle class or giving breaks to the wealthy.

In a speech in Cleveland on Wednesday, Mr. Obama will also make a case for the package of roughly $180 billion in expanded business tax cuts and infrastructure spending disclosed by the White House in bits and pieces over the past few days. He would offset the cost by closing other tax breaks for multinational corporations, oil and gas companies and others.