In the crazy game of presidential politics, where the size of the strike zone is always changing, George Bush is beginning to score in the cornfields of Iowa.

He's not hitting home runs, just scratch singles. But at this early stage of the game that's all anyone can hope for. And Bush has collected enough of them to put him in a league with only Ronald Regan amoung the Republican presidential hopefuls.

The former United Nations ambassador, whose name barely registers on public opinion polls, appears to have taken a surprisingly strong lead over everyone but Reagan in building up an organization to carry him into the Jan. 21 Iowa precinct caucuses, the nation's first formal test in the 1980 race.

The most concrete evidence of this is a series of five straw polls held last week. Bush won four of the informal tests, and is favored to win the fifth when the ballots are counted.

All the straw balloting was amoung party leaders or activists. In a United Press International poll of Republican leaders in 66 of the state's 99 counties, for example, 34 percent of those contacted favored Bush, with 24 per cent for Reagan, 13 percent for Senate Minority Leader Howard Baker (Tenn.), 9 percent for former Texas governor John Connally, and the remaining 20 percent undecided or shared by Rep. Philip M. Crane (Ill.), Sen. Bob Dole (Kan.) and Rep. John B. Anderson (Ill.).

"All these ballots are just so many straws in the wind until someone starts winning them consistently," said Rich Bond, Bush's coordinator for Iowa. "I think we can safely say we're showing some consistency."

"It's a two-man race now in Iowa," he added.

Ironically, an attempt by Bush forces to score an even bigger victory in a "Cavalcade of Stars" fund-raising dinner Saturday night severely diminished its value as a measure of anything more than the ability of the various campaigns to stack the house.

At a similar event last May, Bush won 39.6 percent of the ballots cast by GOP activists; second-place Reagan got 25.9 percent.

Bush needed to win again. And his staff prepared for the $50-a plate dinner like they were readying for the Normandy invasion. They sent out scores of letters and made hundreds of calls trying to get supporters to attend. They rented a band, walkie-talkies, a huge yellow hot air balloon, buses, even a camera crew to follow Bush around.

Opponents did much the same, Baker hired 15 buses and, in newspaper ads, promised free beer, fried chicken and a street dance to college students who would occupy already-paid-for $3 seats which would make them eligible to vote. Connally hired sorority women to skate about wearing tight jeans and T-shirts that said, "Connally Is Rolling."

Supporters of Dole bought $19,750 in tickets to pass out to people who would cast ballots for the Kansas senator. Crane supporters decided to do their own poll -- which they, of course, counted themselves.

Reagan did not attend saying he didn't want to draw a crowd for everybody else.

By the time nine Republican presidential hopefuls arrived Saturday night, there was bad blood all over. Everyone claimed everyone else was trying to buy the straw ballot.

"I'm not trying to buy the election," Dole said. "I'm just trying to equalize it. If we're going to have a poll mania, we have to do something to survive."

"All events are stacked in one way or another. That's how you get a crowd," said Baker. "All of us are participating with our eyes open."

"It's a media event, let's face it," said Anderson, who seemed detached from it all. "It's part of the great circus that goes on. I enjoy circuses I take my children to them all the time."

About 3,500 people attended the dinner, cheering to such campaign promises as one by Crane to move the Agriculture Department to Des Moines if elected. Sen. Larry Pressler (S.D.), campaigning on a gasohol platform, promised a still in every back yard. Harold Stassen promised that if elected he'd go to the Vatican to talk with the pope about morality. California businessman Benjamin Fernandez also spoke.

Results of the straw poll won't be released until Monday by the Iowa Daily Press Association. The reason the candidates put so much significance in them is that in October 1975 Jimmy Carter, then an obscure former governor of Georgia, won a straw ballot at an Iowa Democratic dinner. The next January, he outscored a host of better-known opponents to win the Iowa precinct caucuses, putting him on the way to the White House.

Bush and Crane have openly borrowed Carter's strategy, and have been campaigning strenuously in the state all year. Both, however, are still almost unknown. A Des Moines Register poll, taken in mid-August but not released until today found Bush favored by only 1 percent of Republicans, Crane by 2 percent. Reagan had 40 percent, Gerald Ford 23 percent, Baker 16 percent and Connally 7 percent.

This isn't as meaningful in Iowa politics as it sounds. Only one of every 10 Republicans in the state is expected to attend the precinct caucuses. In short, they are basically an intramural affair for party activists. The emphasis is on building an organization that will be able to bring thousands of voters out in the freezing cold of January.