IN a move that had been anticipated for weeks and that promises to spice up the gumbo of the Louisiana governor's race this year, Gov. Buddy Roemer declared Monday that he is switching to the Republican Party. Mr. Roemer's party switch, believed to be unprecedented for a sitting governor, comes seven months before the state's open primary on Oct. 16. Louisiana's newly Republican governor will be challenged by at least two familiar adversaries - former Gov. Edwin Edwards, a Democrat, and Republican state Rep. David Duke, the former Ku Klux Klan grand wizard.
``At my position in life, and with my vision for meeting the challenges of a new world, a choice must be made,'' Roemer told state and national reporters assembled in front of the governor's mansion here. ``Independence, though admirable, is not enough. My choice is Republican. And the reason is simple. After more than 10 years of public service, it has been my observation and increasing conviction that it is the Republican Party that is becoming the most open to new ideas, new thinking, new people - mo st open to team building, to opportunity building.''
As a four-term conservative Democratic congressman from Shreveport, Roemer voted more with the Reagan administration than with his fellow Democrats. But just as Roemer has angered liberal Democrats in Washington, so has he alienated right-wing Louisiana Republicans by his support for affirmative action and by his nationally publicized veto last summer of a bill that would have given the state the toughest abortion law in the nation.
Recent polls have shown Roemer head-to-head with Mr. Edwards, the controversial three-term Democrat governor whom he unseated in 1987. Edwards declared his candidacy last month. The polls show Roemer running well among Republicans, as he did in 1987. If he can persuade other pary members to stay out of the race, it will strengthen his hand against Edwards.
Three Republicans - former Gov. Dave Treen, US Rep. Clyde Holloway, and US Deputy Energy Secretary W. Henson Moore - had expressed an interest in running before Roemer confirmed his partisan switch.
MR. Duke has said he will run as an independent if he does not get the official GOP endorsement. Polls show his strength down about 10 percent. Both national and state Republican leaders have sought to ostracize Duke, who switched to the GOP to run successfully for the legislature in 1989.
With Roemer's switch, the GOP has picked up two state governors in the last two weeks; Republican Fife Symington was elected governor of Arizona last week in a special election.
Roemer confided last Monday that he had made his decision March 1 after talking by telephone that day with President Bush, a longtime friend. The White House issued a statement which said Mr. Bush had invited Roemer to visit him Monday at the White House.
Bush's support made the switch easier, Roemer said.
Both Edwards and Duke scoffed at Roemer's party switch. ``He's made this decision because he's in bad political trouble and he needs the Republican money and organization to get into the second election,'' Edwards said. If Roemer ``keeps a mainstream Republican out of the race, then it's good for him. But if the Republicans don't keep their agreement, then he's dug his own grave,'' he added.
Duke said: ``If any other Republicans enter the race it assures a David Duke-Edwin Edwards runoff.'' He denigrated Roemer as ``the only Republican I know who's a member of the NAACP [National Association for the Advancement of Colored People] and who supports racial quotas, affirmative action, tax increases, and gun control.''
Under Louisiana's open primary system Democrats, Republicans, and independents appear on a single ballot. If no candidate receives a majority on election day, the two top contenders face each other in a runoff.
Edwards, damaged by two federal racketeering trials - the first ended in a mistrial and he was acquitted in the second - nevertheless ran for reelection in 1987.
Roemer received 33 percent of the primary votes to Edwards's 28 percent, and Edwards declined a runoff, leaving Roemer a minority governor.