Washington — If the past is any indication, Walter Mondale had better put on his political armor for the next four weeks. Just look what happened to other Democratic front-runners at about this time in the campaign:
In 1980, President Carter had been through a bruising battle with Sen. Edward M. Kennedy (D) of Massachusetts. Mr. Carter was assured of the party's nomination, but then lost five of the final eight primaries.
In 1976, Carter, then almost unknown, stunned the party by defeating some of its strongest candidates in state after state. It was clear he would be the party's choice. But in the late primaries, he was drubbed in California, Oregon, and Montana.
In 1972, George McGovern came out of nowhere and led an army of antiwar youth to victory after victory. But he stumbled across the finish line with three defeats in the final eight primaries.
Once again, we're near the finish. There are seven primaries and one statewide caucus to go. And the word to Mr. Mondale from Democratic leaders is: Watch out! Things don't look too friendly out there, especially west of the Mississippi.
The next round of voting comes tomorrow in the Oregon and Nebraska primaries. On May 24, Idaho holds its caucuses. Then the primary season ends with a bang June 5 with voting in California (the year's biggest, with 345 delegates at stake), New Jersey, New Mexico, South Dakota, and West Virginia.
Here's a quick rundown of the outlook, based on talks with top aides in both the Mondale and Hart campaigns:
Oregon. Sen. Gary Hart is favored. His strategists claim this state is almost certain to be in their column, and it's hard to find anyone who will argue with that. Campaign manager Oliver Henkel Jr. says Senator Hart leads in his own private polls there by a ''significant'' margin.
Nebraska. This looks like another Hart state. One week ago, a newspaper poll showed Hart with 39 percent, Mondale with 34 percent, and Jesse Jackson with 6 percent. Mondale aides don't concede the election, but when Nebraska is mentioned, they prefer to change the subject.
Idaho. Hart country.
South Dakota. Probably Hart again.
New Mexico. Mondale - maybe. He has some of the same things going for him in this state that he had in Texas, including the Hispanic vote, which has been almost solidly behind him.
West Virginia. Mondale country.
New Jersey. A pivotal contest. It is seen by both sides as very close. If Mondale suffered a string of losses, this state could be vital in propping up his campaign. He will give it high priority.
California. The grand prize - and central to Hart's hopes. He is believed to be ahead at the moment, but the public's mood is fluid. A victory in the biggest state would bolster Hart's argument that he is the candidate best able to defeat President Reagan. One Hart planner calls the contest ''unpredictable.''
Add these all up, and the message is clear. Mondale probably will still get the nomination. But like Carter and McGovern before him, he will walk into the convention hall knowing there are millions of Democratic voters out there who wish the nominee were someone else.
It's no way to start a campaign against someone like Mr. Reagan, who is already the heavy favorite.
The seriousness of the Democratic situation can be seen when one looks at what is happening over at Reagan-Bush reelection headquarters.
The Reagan-Bush team reveals that it has now raised more than $25 million - the legal maximum - for use before the nominating convention. About $20 million of that will be available to help the President organize his campaign in the 50 states, print election literature, and begin planning for the intense, two-month election drive that will begin after Labor Day.
In addition to the $25 million, Reagan, like the Democratic nominee, will have $40 million provided by the federal Treasury for the fall campaign.
The big war chest means that Republicans will be able to move ahead on scheduled with a $4 million effort to register more voters, mostly Republicans and like-minded independents.
Meanwhile, Hart ($4.5 million in debt) and Mondale ($1.5 million in debt) are putting their efforts almost solely against each other, rather than preparing for the fall showdown.
Even when the final primaries are over, Hart promises to keep the struggle going.
He notes that this year, for the first time in recent history, delegates to the Democratic convention are not legally bound to support any candidate. Hart says he will use the six weeks between the last primary and the convention to win delegates to his cause.
He will hold personal meetings with the delegates, pepper them with phone calls, and flood them with literature - all designed to convince them that he should be the party's choice on the grounds that Mondale has no chance of defeating Reagan in November.