BANGOR — Former state Sen. Stephen Bost, who now heads Ross Perot’s political efforts in Maine, said Friday he is seeking the U.S. Senate seat being vacated by William Cohen.

“I’m going to do it,” said the 39-year-old Bost, who will run as an independent after resigning his posts as New England coordinator of United We Stand America and as state coordinator for the Reform Party.

Bost said a formal announcement would come next week.

“I will run as an independent, but seek the endorsement of the Reform Party once we secure ballot access in Maine,” Bost said Friday. He added that Perot was very interested and aware of the dynamics of the Senate race in Maine and had given him his blessing.

“It’s his assessment as well as mine that it’s very winnable by a strong independent candidate,” said Bost. “Perot’s personal advice to me was, `Go for it.’ ”

There is also a strong likelihood that Perot will campaign for him in Maine, said Bost.

Political sources believe the knowledgeable and affable Bost would fare well in Maine’s 2nd Congressional District, where conservative voters gave Perot his second-highest percentage of the vote during the 1992 presidential election.

“United We Stand America is still alive and well in the state,” Bost said. “You also would want to consider that right now there are about 35,000 people who registered for the Reform Party who were disenfranchised. … Those voters have clearly indicated that they want an alternative.”

A former Democrat from Orono who served 10 years in the state Legislature, Bost believes he will appeal not only to other independents but about equally to Democrats and Republicans.

In announcing his decision Friday, Bost became the fourth candidate to officially enter the Senate race: Former two-term Gov. Joseph Brennan announced his candidacy for the Democratic nomination on Thursday. Brennan’s 1994 campaign manager, former state Sen. Phil Merrill of Hallowell, has been in the race for about a year.

Also on the Democratic side, U.S. Rep. John Baldacci of Bangor is expected to announce early next week whether to enter the primary race or run for re-election to the House.

Businessman and two-time U.S. Senate candidate Robert A.G. Monks has joined the fray for the Republican nomination. Ski mogul Leslie Otten also could run for the nomination.