Washington ? House Republican leaders, through a series of little-noticed rules changes and key appointments, are dramatically tightening their hold on power as they prepare to push for new spending cuts, bigger tax breaks and a more ambitious social agenda.

Since padding their majority in the general election, Speaker Dennis Hastert, R-Ill.. and Majority Leader Tom DeLay, R-Tex., have circumvented the seniority system to reward their most loyal allies with important chairmanships. They have systematically changed internal rules to seize greater authority over rank-and-file members, and unexpectedly scrapped the eight-year limit on Hastert’s reign.

They also are cracking down on wayward members who frequently oppose party leadership positions. Last week, for instance, Hastert privately called in Rep. Chris Smith, R-N.J., and scolded him for challenging the speaker over new bankruptcy laws and other measures, according to members familiar with the meeting.

“Hastert has been able to get more influence, and is poised to exert even more power over the process,” said Hastert spokesman John Feehery.

By centralizing power and demanding discipline, House Republicans are positioning themselves to push President Bush’s agenda through the House and apply greater pressure on the closely divided Senate to adopt more conservative economic and social policies. The new House has 229 Republicans, 205 Democrats and one left-leaning Independent.

In some cases, the Hastert-DeLay team wants to go beyond the Bush agenda. DeLay, for example, says the House should push for deeper tax cuts than the White House has proposed. The Hastert-DeLay team also is mulling as many as six measures to curb abortions.

Bush, looking ahead to the 2004 presidential elections, will feel pressure to appeal to swing voters by de-emphasizing some controversial social issues — such as abortion, perhaps — and being open to compromise on tax and spending measures. Senate Republicans, who hold a two-vote majority, will have a hard time passing legislation without winning over several Democrats. So, Hastert and DeLay are looking to pass as bold an agenda as plausible, knowing they’ll be forced to compromise with Bush and the Senate in the end, House insiders say.

Norm Ornstein, a congressional scholar at the American Enterprise Institute, said the Hastert team’s action “is significant, simply because it’s a sign of an assertion of leadership and a clear signal that Hastert and DeLay wanted to send. It’s shaking things up.”