Television evangelist Marion G. (Pat) Roberston hosted a high-stakes fund-raiser last night, charging up to $25,000 a couple in a presidential exploratory bid that breaks new ground in campaign finance law.

"It's just a small dinner to bring together some folks who are deeply interested in traditional values," Robertson said at a news conference before the event, which he estimated would raise $1 million or more.

Tickets for the dinner and reception at the Washington Sheraton ranged from $1,000 to $25,000 a couple, the latter amount for members of the "host" committee.

Under federal law, a couple cannot give $25,000 to a prospective presidential candidate. However, Robertson will divide the large donations, with $5,000 -- the maximum legal contribution -- going to his political action committee, the Committee for Freedom, and the other $20,000 going to the Freedom Council, according to a spokesman for the tax-exempt organization.

At his news conference, Robertson said that the Freedom Council can accept money from both individuals and corporations, and that the donations are tax-deductible. He said corporations cannot give to federal campaigns, but argued that the money going to the council is "not political money."

He described the council as "a foundation for conservative evangelical principles" and said there is no requirement to disclose contributors. "I don't think we want to publish the list," he said, suggesting that it would violate the donors' privacy.

He declined to name members of the special "host" committee but he described them as businessmen from as far away as Dallas, Phoenix and Seattle.

Among those at the dinner were conservative Sen. Jesse Helms (R-N.C.), who sat at the head table; Cory SerVaas, editor and publisher of The Saturday Evening Post magazine, and Lee Buck, a retired executive of Mutual Insurance Co. of New York and chairman of the Committee for Freedom.

Before the dinner, the gathering of about 130 was briefly entertained by the Mount Vernon Color Guard, students from Virginia schools who wore Revolutionary War-era uniforms and played fife and drums.

In Michigan, a key Republican primary state, the Freedom Council has set up an elaborate network to persuade fundamentalist Christians to run for precinct delegate in the Aug. 5 primary. They will form the pool from which delegates to the 1988 Republican presidential convention will be selected.

Council officials contend that the organization has nothing to do with Robertson's prospective run for the GOP nomination. Nevertheless, the council has sponsored appearances by Robertson, president of the Christian Broadcasting Network, at rallies in Michigan and Iowa, another key state in the delegate-selection process. In Iowa, the council's local leader helped engineer a fundamentalist Christian takeover of the Republican Party in the 4th Congressional District.

The Robertson campaign has been gaining momentum, according to GOP activists, including many who support Vice President Bush or Rep. Jack Kemp (N.Y.).

Robertson indicated a growing interest in running for president. He said that at rallies "I have never seen anything like it, it's electric . . . . There are tens of thousands of people out there cheering."

In judging his prospects, he said, "I'm looking at what the evangelicals do in Michigan. Michigan would be a pretty good sampling of what they are going to do" throughout the election process.

As further evidence of growing support for his candidacy, Robertson cited recent GOP primary victories in Indiana by evangelical congressional candidates whom he had endorsed, despite state party support for their opponents.

Robertson said his evaluation of the Michigan contests suggests that Bush is doing nowhere near as well as expected.

Saying Bush won the 1980 Michigan primary and has the support of much of the GOP establishment in the state, Robertson said he "should be running away with it" when in fact many of the delegate candidates have not indicated that they are for Bush.

This week, according to sources, Robertson split with one of his key political advisers, Jerry Curry, a retired Army officer. Until Monday, Curry was president of the Freedom Council.

According to a spokesman, Curry decided that being president of both the council and a Norfolk think tank called the National Perspectives Institute "was too much work," so he relinquished his council post. Curry was unavailable for comment.