It is not unusual for Republican presidential candidates to call for tax cuts that would expand the deficit: They argue the cuts will spur the economy. But they are now calling for tax cuts in a year in which Washington and many Republicans have been consumed by talk about reducing the deficit. It was only last summer that House Republicans balked at raising the nation’s debt ceiling, citing alarm about high deficits — a move that brought the nation uncomfortably close to a default and led Standard & Poor’s to lower the nation’s credit rating.

By reducing the amount the federal government collects in taxes each year — at a time when federal tax collections are already a smaller share of the economy than they have been in more than half a century — the Republican tax plans will make it harder to balance the budget, said Robert L. Bixby, the executive director of the Concord Coalition, a nonprofit group that advocates fiscal responsibility.

“If the first thing you do is lower revenues by that much by extending all of those tax cuts, then you have a much bigger hole to dig out of to get back to a balanced budget,” he said in an interview. “The hole they’re digging, to mix metaphors, is a self-inflicted wound.”

The tax cuts proposed by the Republicans would more than wipe out the budget-balancing effects of the cuts that were agreed to as part of the compromise that was ultimately reached last summer to raise the debt ceiling. One part of that compromise called for a series of automatic cuts to begin next year with the goal of reducing the deficit by $1.2 trillion over a decade — cuts that some members of Congress are trying to avert on the grounds that they are too onerous. The Tax Policy Center has calculated that by extending the Bush tax cuts, Mr. Romney’s tax plan would add $1.2 trillion to the deficit in just two years. The tax plans offered by Mr. Gingrich and former Senator Rick Santorum of Pennsylvania would add more than that to the deficit in just one year, the center found.

“The amounts of revenue loss we’re talking about in one year is the kind of thing we’re used to seeing over a decade,” said Roberton Williams, an analyst at the Tax Policy Center.

Experts from across the spectrum acknowledge that the Republican tax proposals would benefit the wealthiest the most. Polls have repeatedly shown that a majority of Americans favor raising taxes on households earning more than $1 million a year to reduce the deficit.

Political campaigns are always quick to trumpet tax cuts, but are slow to describe how to pay for them. And campaign proposals, while an important indication of a candidate’s goals, do not always fit with the prose of governing, when any changes must win the approval of Congress. A case in point: As a candidate in 2008, Barack Obama spoke frequently of ending the Bush tax cuts for the wealthiest Americans. As president, Mr. Obama reluctantly extended the cuts as part of a deal with Congress.