KALAMAZOO, MICH. -- Rep. Jack Kemp (R-N.Y.) was out there every day this week throwing bombs, going for it all, daring his party to do the same.

Tuesday night, in Grand Rapids, he said the Republican challenge for 1988 is "how we can win, not 49 states, but all 50 states -- and the District of Columbia."

Early Wednesday, in St. Joseph, he said, "I don't want the Republican Party to be an all-white party, an all-white-collar party, a business party or a middle-class party."

Here, facing a crowd of 125 quintessentially white, middle-class, business Republicans, Kemp, in full cry, said, "I'm telling you, minds are open. We can compete with the liberal wing of the Democratic Party not just in the suburbs but in the center cities, not just in the Sun Belt but in the ghettos and the barrios, if we offer people more than fiscal austerity."

Each Kemp speech on a swing from Minnesota to New Hampshire ended with an invitation to join what he likes to call "the progressive, conservative, radical, revolutionary, Lincoln emancipation" wing of the Republican Party -- embodied, of course, in his candidacy for the 1988 GOP presidential nomination.

Radical may not be too strong a word for the Kemp platform, which ranges from flat opposition to any increase in taxes and any cut in Social Security or "safety net" spending, to early deployment of a space-based antimissile defense system and rejection of any new treaties with Moscow until the Soviet Union satisfies the terms of every past agreement, "going back to Yalta," as he specified at several stops.

To some observers of the Republican nomination struggle, reading polls showing Kemp a distant third to Vice President Bush and Senate Minority Leader Robert J. Dole (Kan.) -- these "bombs" of Kemp's are the desperation passes a losing quarterback throws as the clock ticks away the final seconds of the fourth quarter.

He has been on the road for six months delivering his message and even his own managers admit he has not ignited a prairie fire. Kemp has long believed that as the original sponsor of the deep tax cuts that were at the heart of "the Reagan revolution," he is the president's spiritual heir. The polls so far show little acceptance of that notion, but Kemp still thinks that if Bush or Dole stumbles, if he can go "one-on-one with an Old Guard Republican," he will win.

The reactions in Kemp's audiences of Republican activists on a three-day swing were mixed, some converts, some reiterated skeptics.

But the far more important tests will start on Oct. 28 in the first televised GOP candidates' debate. Then, and only then, will there be a chance to see if rank-and-file Republican voters think Kemp is right when he says that "the Republican Party has learned a lot under Ronald Reagan, and it's more positive, adventuresome, entrepreneurial and ready to take a risk."

Risk-taking is a way of life for the Kemp campaign, on the realistic assumption that if Republicans want to play it safe, they will pick the more heavily credentialed and conventional Bush or Dole. In a backhanded swipe at the two leaders, who present themselves as pragmatists, not idealists, Kemp told the audience in St. Joseph, "The Republican Party cannot be a party of the status quo. People will forgive you a lot but they will not forgive you a lack of vision for the future."

Kemp's vision is nothing if not sweeping. It reaches from "defense of the unborn" through restrictions on abortion to "support of freedom-fighters," including the anti-Sandinista contras in Nicaragua, whose cause Kemp frets Reagan may have compromised by State Department soft-liners.

Some in his audiences find this a heady mixture and walk away impressed. Jim Ippell, a businessman and an uncommitted precinct delegate, pronounced himself "very impressed" at the end of Kemp's talk here. "He's very clear on what he believes. He has a positive sense of what our party and our country need. It's more than politics to him."

Others, like stockbroker Marty Gatchell, are plainly skeptical. Kemp told Gatchell in St. Joseph that "the only way to balance the budget is by economic growth," not raising taxes, cutting defense or reducing help to the elderly and the needy. "We've tried the growth route with Ronald Reagan," Gatchell said afterward, "and look where we are."

A major target on Kemp's swing through Michigan were precinct delegates elected to the Jan. 29 state convention by church groups allied with Marion G. (Pat) Robertson. The loose Robertson-Kemp coalition, joined in some places by Dole backers, has taken control of the state GOP committee from pro-Bush "regulars" and hopes to repeat that victory in the state convention that will open the 1988 GOP delegate contest. Kemp would be well-satisfied to be a runner-up to Robertson in Michigan.

For Iowa's Feb. 8 caucuses, the next contest, there is no deal with Robertson -- and far more danger to Kemp. Bush won Iowa in 1980 and Dole has achieved at least parity in the polls. Charles Black, Kemp's top political operative, calls Iowa "the worst state in the country for a candidate like Kemp," partly because the farm economy has not shared in the bloom of "Reaganomics" that Kemp hails in every speech and partly because "even the conservatives aren't gung-ho about defense and SDI {Strategic Defense Initiative} there."

Robertson threatens Kemp with a fourth-place Iowa finish, and Kemp conceded "a distant fourth would be an absolute disaster" but "a close four-way finish might not be detrimental . . . . "

In New Hampshire, the first primary state, Kemp is running second or third, depending on the poll, and his organization -- bolstered by allies of Sen. Gordon J. Humphrey (R-N.H.) and Rep. Robert C. Smith (R-N.H.), both Kemp supporters -- is rated second only to Bush's. And in Minnesota, the third state he visited on this week's swing, he is viewed by many as the early favorite, having just won a state convention straw poll over Dole.

Minnesota's Feb. 23 caucuses are a week after New Hampshire and just ahead of the March 8 "Super-Tuesday" primaries. Kemp's organizing in those states has been hampered, campaign chairman Edward J. Rollins concedes, by the relative skimpiness of his finances ($5.5 million raised through Sept. 30, compared with $12.3 million for Bush and $7.5 million for Dole.) But money has been committed to a media campaign that will start in Iowa and New Hampshire next month.

Of greater short-term significance to Kemp are the televised Republican debates that will begin Oct. 28 with William F. Buckley Jr.'s "Firing Line" forum. "Those debates will be very important for me," Kemp said in an interview Wednesday. "I've made my reputation as a guy who promotes ideas, who has a lot of specificity, and I have to show that my ideas deserve to be taken seriously."

In stump speeches this week, Kemp proved he could discipline his verbosity and drive home his main points of difference with his rivals. "Two years ago, at our Lincoln Day dinner," said Grand Rapids lawyer Dave Kamm, "he was dull, just regurgitating platitudes. Tonight, he was much brighter and more spontaneous."

Another person who has seen that improvement is Kemp's House colleague, Democratic presidential candidate Richard A. Gephardt (Mo.). After besting Kemp in their first debate in Iowa last summer, Gephardt came away with a draw on most score cards when they tangled again last month, in New Hampshire. "Jack did well," Gephardt said afterward. "I think he's going to surprise some people."