WASHINGTON — As the Senate edged toward a divisive filibuster vote on Chuck Hagel’s nomination to be defense secretary, SenatorTed Cruz, Republican of Texas, sat silent and satisfied in the corner of the chamber — his voice lost to laryngitis — as he absorbed what he had wrought in his mere seven weeks of Senate service.

Mr. Hagel, a former senator from Mr. Cruz’s own party, was about to be the victim of the first filibuster of a nominee to lead the Pentagon. The blockade was due in no small part to the very junior senator’s relentless pursuit of speeches, financial records or any other documents with Mr. Hagel’s name on them going back at least five years. Some Republicans praised the work of the brash newcomer, but others joined Democrats in saying that Mr. Cruz had gone too far.

Without naming names, Senator Barbara Boxer, Democrat of California, offered a biting label for the Texan’s accusatory crusade: McCarthyism.

“It was really reminiscent of a different time and place, when you said, ‘I have here in my pocket a speech you made on such and such a date,’ and, of course, nothing was in the pocket,” she said, a reference to Senator Joseph R. McCarthy’s pursuit of Communists in the 1950s. “It was reminiscent of some bad times.”

In just two months, Mr. Cruz, 42, has made his presence felt in an institution where new arrivals are usually not heard from for months, if not years. Besides suggesting that Mr. Hagel might have received compensation from foreign enemies, he has tangled with the mayor of Chicago, challenged the Senate’s third-ranking Democrat on national television, voted against virtually everything before him — including the confirmation of John Kerry as secretary of state — and raised the hackles of colleagues from both parties.

He could not be more pleased. Washington’s new bad boy feels good. MORE BAD ASS SENATOR