It was suggested to George Bush on national television today that he liked issues better than political nuts and bolts.

"Not necessarily," Bush interjected in an ungraded burst of candor.

Indeed, nuts and bolts may well be the decisive factor in Monday's Iowa caucuses, the first important, if somewhat overblown, contest of the 1980 presidential campaign.

Issues have hardly seemed worth arguing over here, as both Democrats and Republicans -- except, perhaps, for Illinois Rep. John B. Anderson, a liberal Republican -- try to outdo each other in hawkish rhetoric.

Campaigning through Iowa this frosty weekend, Bush, the affable former chairman of the Republican National Committee, revved up his organization -- the envy of his rivals -- from Sioux City to Cedar Rapids.

Political veterans here predict that Bushs could come close to upsetting front-runner Ronald Reagan if there is a low caucus turnout. With a high turnout, however, Reagan would have a clear advantage, they say. Senate Minority Leader Howard H. Baker Jr., also campaigning here, could draw supportd from Bush, further strengthening the showing of Reagan, who himself has put together a sophiscated campaign organization.

Today Bush, buoyed by warm receptions in five Iowa cities, could hardly contain his enthusiasm. Reagan, he said, "is going to be stopped by me and he's got to be stopped by me and he's got to be stopped before Illinois or he's got the nomination." The Illinois primary is March 18.

Bush was attacked in a half-page ad in the Des Moines Register today reprinting an editorial from New Hampshire's Manchester Union Leader. "Liberal and leftist newspapers hope Republicans pick Bush . . . easiest to beat, closest to their idealogy if he wins!" the ad read. Bush staff members attributed the ad to a supporter of John B. Connally, a Republican rival.

For all contenders, foreign policy is the most popular vehicle to demonstrate leadership, resolve and vigor -- the qualities they assert President Carter lacks. "We have to turn around what has been a weak, vacillating foreign policy under Jimmy Carter," Bush told CBS television on "Face the Nation" today.

"Every time we look like we're unwilling to do anything, the Soviets step forward. They're going to continue to do that until they see a policy that's going to stand up against aggression."

Bush attacked Carter for not funding some weapons programs, among them the B1 bomber, the neutron bomb nad sufficient naval improvements. He said he opposes a grain embargo except in the context of a total economic embargo, but stopped short of advocating one.

While many foreign policy experts now fear that further pressure on Iran will encourage Soviet aggression there, Bush said that if Carter imposed a unilateral blockade of Iran, "I would certainly be out there in the forefront saying he had done the right thing."

Reagan, who has been criticized for not spending more time in Iowa, gave a live television speech here Saturday night. Framed by his slogan "Let's Make America Great Again," he ridiculed Carter for just discovering that "you can't trust the Russians. A great many of us could have told him that a long time ago."

Bush is stressing his experience as ambassador to China and to the United Nations, and as director of the Central Intelligence Agency. His staff points out that Reagan has no foreign policy background. After a Bush speech in Davenport today, Ginny Wiklund, a 37-year-old housewife, said, "Six months ago, foreign policy meant nothing to me. Now it's very important to me."

Veteran Iowa political workers, however, say the outcome of the caucuses will have little to do with such issues. "TV ads aren't going to get people out on a cold January night," said Ralph Brown, former director of Iowa's Republican Party. "It takes person-to-person contact. A lot of it is one-on-one retail politics."