Howard E. Phillips, chairman of the Conservative Caucus, filed a formal complaint yesterday against Vice President Bush, the Republican National Committee and Bush's political action committee (PAC), charging that they plan to illegally finance a poll that tested the vice president's 1988 presidential prospects.

The complaint to the Federal Election Commission dismisses as "ludicrous" plans to share poll costs among the RNC; Market Opinion Research, a polling firm, and the Fund for America's Future, the Bush PAC.

While raising complex issues of campaign finance, the Phillips charges implicitly question the RNC's neutrality in the contest for the 1988 Republican presidential nomination. William Greener, RNC political director, countered: "We are as pure as the driven snow."

The Bush PAC, the RNC and the polling firm have been unable to reach an agreement on payment for the controversial poll after seven weeks of discussions.

"People have been haggling since this thing blew up," Jan Baran, lawyer for Bush's Fund for America's Future, said. "There is a bona fide dispute among the Bush PAC, Market Opinion Research and the RNC over who ordered what and who is going to pay for it."

Market Opinion Research recently sent a $70,000 bill to the RNC for the poll, but Greener said he returned the bill to make sure the RNC would not be paying for any questions that it had not authorized.

The controversy stems from the disclosure in early December that an RNC survey had been used to evaluate Bush's chances "in the primary and general elections for president in 1988." The disclosure provoked angry changes from likely Bush challengers that the poll amounted to an illegal $70,000 contribution to Bush's undeclared campaign.

RNC and Bush PAC officials claimed that questions in the poll concerning Bush's presidential chances were mistakenly added by Robert Teeter, president of Market Opinion Research who is a Bush consultant. The officials said poll costs would be divided among Market Opinion, the RNC and the Fund for America's Future.

Phillips' complaint contends there is no legal way to pay for the poll under federal campaign law unless Bush pays or forms a special presidential exploratory committee, politically embarrassing steps to Bush.