While he now demands that higher tax rates for the wealthy must be part of a “fiscal cliff” deal, President Obama took a very different line just over a year ago in the last major clash with Congress over a long-term budget deal.

In comments Republicans on Capitol Hill are highlighting, Mr. Obama argued in the summer of 2011 that the government could raise more than $1 trillion in revenue without increasing tax rates paid by the rich — something the president now contends is mathematically impossible.

“What we said was, give us $1.2 trillion in additional revenues, which could be accomplished without hiking taxes — tax rates — but could simply be accomplished by eliminating loopholes, eliminating some deductions and engaging in a tax-reform process that could have lowered rates generally while broadening the base,” the president said at a July 22, 2011, White House news conference.

Mr. Obama’s position today is that his $1.6 trillion plan to avoid the fiscal cliff of tax increases and deep spending cuts must include higher tax rates for the top 2 percent of the income scale.

“It’s not me being stubborn. It’s not me being partisan. It’s just a matter of math,” Mr. Obama said this week in an interview with Bloomberg.

During remarks to corporate CEOs at the Business Roundtable on Wednesday, Mr. Obama called on the leaders to urge Republicans to accept the tax-rate increases and not to use the debt ceiling to gain leverage for more entitlement cuts in the fiscal-cliff negotiations.

The president made the comments on a day when he and House Speaker John A. Boehner, Ohio Republican, spoke by phone about a deal to avoid the fiscal cliff. Aides to both men gave no details about the call, and no plans for a face-to-face meeting were announced.