"Substituting for Ronald Reagan at a gathering of Republicans," Vice President George Bush told nearly 3,000 over dinner at the Washington Hilton last night, "is a little like being called on to pinch-hit for George Brett in Kansas City." But he did, beginning his party's war cry against House Democrats in the elections of 1982.

If there had been any more Republicans squashed into this annual Senate-House dinner last night, they'd have hung them from the bunting. You could hardly get an extra-dry Rob Roy as it was, what with the back-up at the bars. Such are the sacrifices of the majority party.

"It's interesting how many new friends we've found since November," observed Oregon Sen. Robert Packwood.

Reagan had been the scheduled speaker until last Monday's assassination attempt, so Bush had the job of Republican cheerleading. "We have Howard Baker as Senate majority leader," he said. "Now we need -- and President Reagan needs -- Bob Michel as speaker of the House of Representatives."

Bush also had the job of pushing the president's economic program at a key time. Bush was forceful ("You cannot nickle and dime this program to death!") and he was imploring ("We need your help in holding this together!"), but he was not Ronald Reagan.

"Nobody is," sighed presidential counselor Edwin Meese.

"Be nice to have him here, wouldn't it?" said White House chief of staff James Baker.

The Republicans hold this $1,000-a-plate fund-raising dinner every year at the Hilton, and generally, the ambience is mass glitter. But this year, there was a slight sense of the macabre as guests arrived via the sidewalk where Reagan had been shot last week.

"It was very poignant, coming here tonight," said White House staff director David Gergen. "Where I drove up to the entrance, I couldn't help but think."

Security at the Hilton was extremely tight. Guard dogs sniffed out bathrooms, reporters' bags were searched, and police and Secret Service agents seemed to pop up everywhere. Nancy Reagan had been scheduled to attend, but yesterday, at the last minute, she decided to have dinner with the president at George Washington University Hospital.

Much of the evening at the Hilton was taken up by speeches that turned into a political lovefest.

"This is the most successful fund-raising event in the history of the United States," cried Packwood in remarks from the podium. "We have grossed in excess of $3 million." It's to go toward the 1982 Republican congressional campaigns. His party may have the presidency and the Senate, but now they want the House.

"We're off to a good start," said Baker at a before-dinner reception. "There's a good chance that we'll make substantial gains in these next years. I expect three seats in the Senate, and I think there's a 50-50 chance we'll get control of the House."

Few in this crowd were inclined to make much -- at least publicly -- of the Democratic economic program offered this week as an alternative to the president's. "It's so much closer to our proposal than the traditional Democratic program that I think it's fascinating," said Murray Weidenbaum, chairman of the Council of Economic Advisers.

Weidenbaum was one of the few administration stars spotted at the crowded reception where getting an elbow in your wine glass was a frequent occurrence. Most of the White House celebrities avoided this by arriving late, just before dinner. So most of the reception crowd appeared to be well-to-do contributors.

"Look, she's got a new bracelet," one woman said to a second. She was pointing to something sparkling and heavy on a nearby wrist.

"Aaaaaaaah," said the second woman, "I won't be able to see for all the diamonds."