DES MOINES -- Lamar Alexander gets a laugh when he suggests that Steve Forbes should ''broaden his experience'' by running for the school board or president of the Kiwanis Club before seeking the Republican nomination for president of the United States.
But Mr. Alexander is dead serious. His chances of surviving the Iowa caucuses next Tuesday and the New Hampshire primary eight days later depend heavily on whether he can cut Mr. Forbes down to size.
If he succeeds, the former governor of Tennessee might finish a respectable enough second or perhaps a very close third here and thus be anointed as a serious contender in New Hampshire. But if he trails with less than 10 percent of the vote, his candidacy will lose much of its credibility in New Hampshire.
Mr. Alexander's own polling, his advisers say, suggests he is at least in the game here. A telephone survey of 300 Iowa voters the other night, they say, found Senate Majority Leader Bob Dole with 30 percent of the vote, Mr. Forbes with 15 and Mr. Alexander with 11.
Opinion polls are notoriously unreliable in forecasting the results of the precinct caucuses here, which turn so much on the ability of campaign organizations to get their supporters simply to show up. So the Alexander figures, even if accurate, should be viewed skeptically.
But if Steve Forbes has a vulnerability as a candidate, it is his lack of conventional credentials. The fact that the wealthy magazine publisher is not a politician is both his greatest asset and his heaviest burden.
He gave Mr. Alexander an opening by saying on a Sioux City radio talk show that he might phase out a federal tax break for ethanol, a product that provides a huge market for Iowa corn growers.
Mr. Alexander quickly asserted before a farm group here that ''anyone from the real world would know'' that this is the ''wrong time'' to pull the rug out from under the corn growers. That is the core of his case -- that he is a ''candidate from the real world'' in contrast to the Washington politicians and Mr. Forbes, who has never run for public office.
There is, of course, no assurance that cutting Mr. Forbes down to size necessarily will benefit Mr. Alexander. Some of those intrigued by the magazine publisher may decide instead on the safe, known quantity, Senator Dole, thus reinforcing his position as the leader of the Republican field. Other polls show Sen. Phil Gramm of Texas as the prime competition here for Messrs. Dole and Forbes.
Cut their pay . . .
But Mr. Alexander has few cards still to play. The original theme of his candidacy -- ''Cut their pay and send them home'' -- had to be scrapped or at least muted when his fellow Republicans became the ones controlling Congress. And his self-description that he was the true ''outsider'' in the field of Republicans obviously lost some force when the total amateur Mr. Forbes suddenly emerged as a serious factor in the equation.
But Mr. Forbes clearly has given some weight to the Alexander challenge. His campaign is running a 30-second television commercial that argues that rather than being a true outsider, the former White House aide and Cabinet secretary is a highly paid lawyer whose firm lobbies Congress and thus would ''fit right in'' in Washington.
Sources who should know say Mr. Forbes was personally irked and ordered the televised attack on Mr. Alexander, who called his flat tax plan ''a nutty idea'' during a debate here last month.
Going into the final days of the Iowa and New Hampshire campaigns, Mr. Alexander has one advantage on the others pursuing Senator Dole -- personal approval ratings twice as high as his disapproval, perhaps because he has run far less negative advertising than the others.
But his message here, although delivered with good humor, is every bit as harsh and direct. He is saying Bob Dole is too old to defeat President Clinton and that Steve Forbes simply lacks the credentials to hold the office. The question is whether enough voters are listening to keep his campaign alive.
Jack W. Germond and Jules Witcover report from The Sun's Washington bureau.