The somewhat frozen smile on the face of former vice president Walter F. Mondale, campaigning before tonight's Orioles game, broadened when he spotted Patricia Hughes, wife of Gov. Harry Hughes.

"Pat," he said, reaching to grasp her hand, "it's good to see you. It's been such a long time."

Actually, Mondale has seen a lot of the Hugheses in the last few months. Tonight's fund-raiser in the bullpen area behind the centerfield fence in Memorial Stadium--"Take me out to the ballgame with Fritz," it was called--marked the fourth time Mondale has appeared in Maryland in less than a year and in all likelihood was his last appearance here for several months.

His apparent pleasure at seeing Patricia Hughes again may have had a lot to do with his political standing in Maryland, where a poll released this week shows him with 38 percent of the Democratic vote compared to only 20 percent for Sen. John Glenn (D-Ohio), his main competitor for the Democratic presidential nomination next year.

What's more, Mondale has had most of the state's top officeholders lined up for him since March. Hughes, Lt. Gov. J. Joseph Curran Jr., Sen. Paul S. Sarbanes and Attorney General Stephen H. Sachs, all early Mondale supporters, all showed up tonight and all seemed convinced that Mondale was still the frontrunner, not only here but across the country.

"He's the better candidate, it's that simple," said Hughes. "Look at him, he handles himself well. You always worry about what the other candidates are doing, but I think he's going to win."

Most in the crowd of about 750 paid $100 each to eat hot dogs, drink beer and, afterwards, take in the Baltimore Orioles-Detroit Tigers baseball game. The affair was put together by Baltimore lawyer Ronald Shapiro, the agent for several Orioles players. Shapiro said his goal had been to raise $80,000 for the evening and, "I'm pretty sure we'll make it."

Most of the political organizing was done by Sarbanes, Mondale's campaign manager here. "This is a good state for him and he knows it," Sarbanes said. "That's why he's comfortable in this crowd."

Whether Mondale was comfortable or not, he told the audience that being in Baltimore always made him feel better and, after giving his throw-the-Republicans-out-of-the-White-House speech, concluded by saying, "I'd like to do as president for the country what the people of Baltimore have done for this city."

That got him a big cheer. After that, everyone headed for box seats next to the third-base dugout to watch the baseball game.

One notable absentee was Rep. Steny H. Hoyer (D-Md.), who was tied up in Congress and couldn't make the affair. Hoyer, after considering going with Glenn, has decided to endorse Mondale. This week, he called legislators from Prince George's County and asked them to be sure to come to the fund-raiser.

"I can't believe I'm here and Steny isn't," said State Sen. Thomas P. O'Reilly (D-Prince George's). "He calls me and asks me to come and then he doesn't show." O'Reilly shrugged. "It doesn't matter anyway. The way old Reagan's been going, Fritz doesn't have a prayer and neither does any other Democrat."