A new tax cut is emerging to rival those of the Bush years, and the deficit hawks have hardly peeped.

“It’s a great talking point when you have an administration that’s Democrat-led,” said Representative Mark Walker, Republican of North Carolina and the chairman of the Republican Study Committee, a group of about 150 conservative House members. “It’s a little different now that Republicans have both houses and the administration.”

For years, Republican lawmakers lamented the soaring national debt, pressing for spending cuts and clinging to the mantle of fiscal responsibility. But last week, Senate Republicans hammered out a deal to allow for as much as $1.5 trillion in tax cuts, betting that supercharged growth will make up for lost revenue, a potentially dubious prospect. The tax plan outlined Wednesday by the White House and Republican leaders in the House and Senate could cost more than $2 trillion over the next decade, according to a preliminary estimate by the Committee for a Responsible Federal Budget.