MORE than anything else, Iowa 1988 will be remembered as the beginning of the end for the Republican Party's chances of capturing the White House in 1988. Former television evangelist Marion "Pat" Robertson's startling second place finish in the caucuses on Monday night has destroyed the party's chances of ever again attracting the voters who gave Reagan his landslide victories.

Caucus winner Senator Robert Dole and Vice President George Bush had thought 1988 would be a two-man race. But Robertson's Iowa result boosts him into the front of the pack by demonstrating that his victories in Michigan and Hawaii were not mere flukes.

Bush, who trailed Robertson by 6 percent in a weak third place, will not be the only one to suffer from Robertson's strong showing. Dole will now have to square off with a candidate who commands the loyalty of zealous extremists from the Republican far Right.

Dole or Bush may be able to soothe the fears of some moderate Republicans, but the influence of Robertson's extremist disciples in the party will be undeniable. If his luck continues, Robertson could emerge from the primary season controlling a sizeable portion of the convention delegates, poised to shape the Republican platform. In the last two elections independents and defectors from the Democratic party, mesmerized by Reagan's charisma, chose to ignore the Republican Party's beholdenness to the far Right; this time they won't have that chance.

Robertson's surge badly embarassed the Vice President, but has by no means knocked Bush out of the race. The Bush campaign has stockpiled the most campaign funds of any Republican in the race and has pledged to stay in the campaign for the long haul. Bush, who owns a home in Maine, remains competitive in neighboring New Hampshire and has been dominating the polls there by a wide margin. A strong rebound for him in next Tuesday's primary could be viewed by voters as evidence of his resilience.

In the Democratic caucuses, what did not happen was more noteworthy than what did. No candidate scored a knockout blow, since first place finisher Rep. Richard Gephardt (D-Mo.) won by only 4 percent. The failure of any candidate to separate himself from the pack signals that the race may go all the way to the convention.

Another significant event that failed to liven up the caucuses was a victory by Massachusetts Gov. Michael Dukakis, which would have defined the Easterner as a viable national candidate. Added to a win a week later in New Hampshire, where Dukakis is widely viewed as the odds-on favorite, an Iowa victory would have catapulted him into the South as the Democratic frontrunner.

Dukakis' grasp on 21 percent of the Iowa vote may come to be viewed as proof that he is not merely a regional candidate--if his campaign can put enough spin on the results. In addition to leading in the East, Dukakis at times vied for the lead in Iowa with the Midwestern candidates, Gephardt and Sen. Paul Simon (D.-III.). A month ago, however, instead of waging a full scale campaign in a caucus vote he might not have won, Dukakis started to portray the vote as a mere prelude to New Hampshire. His campaign billed the winner of Iowa to be a mere challenger to Dukakis in New Hampshire. By lowering expectations for Iowa, Dukakis neutralized the potential damage of a third-place finish.

ANOTHER potential disruption to the race that did not occur in Iowa was Gephardt's elimination--which would have resulted from anything short of victory. Down in the polls as recently as two months ago, Gephardt concentrated his national staff in Iowa and unleashed a blitz of new commercials portraying him as an anti-establishment populist. A win was absolutely essential for the congressman, who had campaigned strenuously in Iowa for nearly two years.

Gephardt's risk has paid off. An Iowa victory gives him a tremendous boost in national media attention. However, his populist image, responsible for his campaign's rejuvenation, may prove unsaleable in New Hampshire. Calls for protectionism and an oil import fee may be popular among the disgruntled residents of the depressed Midwest, but they won't fly with New Hampshire voters.

Had Simon won in Iowa, the race may have become the two-man contest--between him and Dukakis--that it promised to be before Hart's return in the fall. Enjoying a much stronger organization in New Hampshire than Gephardt, Simon looks to do well in next week's primary. An Iowa victory and the attendant media exposure would have enabled him to run an even stronger challenge in New Hampshire, where a narrow loss to Dukakis would be a triumph. Coupled with an Iowa win, this would have provided Simon with front-runner status going into Super Tuesday.

A result from Iowa that may not receive as much press as it deserves is Rev. Jesse Jackson's hold on more than 10 percent of the vote. In a state where only I percent of the population is Black, this result proves Jackson is a more broadly-based candidate than some observers believe.

But the Iowa result that deserves the most attention come November is the strong showing of the other Reverend-turned-candidate. Robertson's second-place finish discloses the Republicans' Achilles heel. Should Robertson continue to pick up delegates and turn off moderates, it will not matter which Democrat opposes the Republicans in November. Even godless Gary Hart, with 0 percent of the Iowa vote, would have a shot.