Recently retired White House political director Edward J. Rollins said yesterday that Democratic ineptitude in Congress and the capture of the Achille Lauro terrorists have enabled President Reagan to escape a serious political trap and head into the Geneva summit "on a high" of public support.

Rollins, who resigned two weeks ago to become a private consultant, told a group of reporters that the Democrats have "missed a unique opportunity" to wing Reagan on the issues of budget deficits, trade and South Africa.

"We expected a very rough autumn on Capitol Hill," he said, "and we thought he would go to the summit in a weakened position." Instead, Rollins said, Reagan "has captured the public imagination again" by snaring the four terrorists and has a big stock of political capital on which to draw in dealing with the Russians.

He said that domestically, Reagan had been skillful in defusing the trade and South African issues and had managed to put the Democrats on the defensive by endorsing the Gramm-Rudman deficit-cutting plan at the very time "we expected the Democrats to be nailing us for the $2 trillion national debt."

Rollins, who managed Reagan's reelection landslide, said Reagan's strength would likely carry over to the 1986 mid-term election year, whatever happens in Geneva or on tax reform.

"I don't expect a deal at the summit," he said. "I hope they Reagan and Soviet leader Mikhail Gorbachev get along well and agree to keep the negotiations going. That is a home run for our purposes."

As for predictions that Reagan's spotlighted tax bill may be delayed and diluted in Congress, Rollins said there would be "zero impact" politically even if it flops. As long as the economy stays healthy, he said, voters won't "keep a scorecard" on Reagan's legislative successes and failures.

The GOP strategist was very cautious about the outlook for continued Republican control of the Senate, saying "I expect to lose three or four Republican incumbents but pick up a couple of Democratic open seats" in Louisiana, Missouri and possibly Colorado. "I'm not optimistic about beating any Democratic incumbents," he said, "but we could hold on to a 51-49 margin."

Rollins said he will handle Republican senatorial challengers in California, Colorado and Louisiana, among other states, but his most interesting unpaid client is evangelist Pat Robertson, who he said is contemplating a bid for the 1988 Republican presidential nomination.

Rollins said he has told Robertson that he is committed to Vice President Bush in the 1988 race, but will help the Virginia Beach television preacher set up a political action committee and campaign for Republican candidates in 1986.

Rollins said Robertson can raise at least $2 million or $3 million for his PAC from his 2.5 million listeners and supporters, adding that "it's very important to the future of the Republican Party that he and his constituents continue to be involved in our party.

"We have to keep the support of the Yuppies who tend to be libertarian and at the same time hold the religious right," Rollins said, "and the more we can keep people like Robertson out front and involved in the Republican Party, the better off we will be.

"I think he is more responsible, more political and pragmatic than some of the other preachers. He wants to be a major player in the Republican Party and I think he can be."