Phil Gramm didn't look any different at the Hyatt Regency last night. Or act any different. Or say anything he hasn't already said.

Oh, but all the Republicans on hand nibbling quiche and pineapple knew the real truth. After merely six weeks away, he was a new man.

Now, he was one of THEM.

At a jammed-packed party befitting the GOP, Texas Rep. Phil Gramm was welcomed back to Washington and into the Republican Party last night with much fuss and fanfare. After all, it's not everyday a Democrat quits Congress and defects from his party two months after winning an election, and then runs again as a Republican. And wins.

"I'm just the same old dull congressman," offered Gramm, pumping the flow of hands filing into room. A few minutes later though, Gramm was more energized, pledging to be a "good soldier in the Republican army."

"You all probably think that the Democratic leadership never offered to have a party like this for me," Gramm continued, while everyone paused, mid-egg roll. "They did. All I had to do was offer to be burned at the stake."

The crowd ate it up. He's a real hero these days. Last January, for the first time in 70 years, the Democratic leadership voted to strip a member of his committee seat because of party disloyalty. Gramm was unceremoniously dumped from the powerful House Budget Committee for consorting with David Stockman.

An outspoken booster of Reaganomics for almost as long as Reagan has been, Gramm promptly switched parties and returned to Texas to run in a special election last month. He won with 55 percent of the vote, and Republicans held a seat for him on the Budget Committee.

"He was philosophically and fundamentally a Republican before he switched, so that's all the same," said Sen. John Tower (R-Tex.), wearing canary-yellow plastic sunglasses with little red lights on them. "And your personality doesn't change if you switch parties. I was born a Democrat myself and I got over it."

"It will help on the budget," said Sen. Robert Dole (R-Kan.), chairman of the Senate Finance Committee. "It would be even better if we had those other 26 seats back that we lost. This is sort of a hard way to do it."

The party was cohosted by the Republican National Committee and the National Republican Congressional Committee, both of which heavily financed Gramm in the special election. The room was mainly packed with Hill staff aides and Gramm friends.

At the end, Rep. Guy Vander Jagt (R-Mich.), chairman of the NRCC, called Gramm "the brightest, most articulate star in the Republican constellation."

Then he showed everyone the golf tees he and Gramm received from President Reagan when they visited the Oval Office last week. They weren't ordinary golf tees. They had a special messages on them: Stay the Course.

Everyone laughed and went back to the egg rolls.