On a July evening in the Capitol, Vice President Dick Cheney summoned three Republican senators to his ornate office just off the Senate chamber. The Republicans - John W. Warner of Virginia, John McCain of Arizona and Lindsey Graham of South Carolina - were making trouble for the Bush administration, and Mr. Cheney let them know it.

The three were pushing for regulations on the treatment of American military prisoners, including a contentious ban on "cruel, inhuman or degrading treatment or punishment." The vice president wanted the provision pulled from a huge military spending bill. The senators would not budge.

"We agreed to disagree," Mr. Graham said in an interview last week.

That private session was an early hint of a Republican feud that spilled into the open last week, as Senate Republicans openly challenged President Bush on American military policy in Iraq and the war on terrorism. In the center of the fray, pushing Congress to reassert itself, were those same three Republicans.