The fight to finish building the beleaguered $2.3 billion Seabrook nuclear power plant has shifted from the streets to the boardroom, where it faces its toughest foe-the tightfisted financial community.

The colorful placards of the fiery nuclear power protesters have been replaced by memorandums from coolheaded investment bankers pulling the plug on the utility company's plan to sell $400 million in bonds to help build Seabrook.

"The company's operations are not shaky; we're just not showing enough of a cash flow to finance Seabrook," said Gordon McKenney, spokesman for the Public Service Co. of New Hampshire, the private utility building the plant.

With 10 years and $500 million already invested in the twin reactor facility-now a symbol of the national battle over nuclear power-the utility company is stepping up efforts to come up with the money.

The board of directors of Public Service Co. voted today to sell 200 million shares of common stock sometime next month to raise $40 million help finance the atomic facility.

"We're buying some time until we come up with a sufficient way to finance it," said company spokesman Gordon McKenney. The company recently threatened to halt construction by Christmas unless it could solve some of its financial difficulties immediately.

Among the company's other alternatives is to sell off a portion of its 50 percent stock in the power plant to one of the nine co-owners-a move that, because of federal regulations, could mean a one-year construction delay.

"If we didn't have to build Seabrook we'd be fine," McKenney said. "We wouldn't have the Clamshell Alliance demonstrating on our doorstep; we wouldn't have to put up with the legal hassles and the federal regulatory hearings.

"Everything would be great-until we ran out of electricity in the early 1980s."

Threats of impending brownouts and blackouts-the company has devised an emergency plan to shut off electricity for a couple of hours at a time in different portions of the state on a rotating basis so that it doesn't run out of power completely-are part of a heavy lobbying campaign to convince state legislators to provide backing for the company's bonds.

Legislative leaders, for the most part, said they would support the plan only if it did not hurt the state's AAA credit rating. Others were vehemently opposed.

"Public Service Co. is not owned by the state of New Hampshire, so why should people of New Hampshire pay for it? If something goes wrong, let their stockholders pay for it," said state Sen. Clesson Blaisbell. "I can't see the legislature taking responsibility for the bungling management of the Public Service Co.; that's not our repsonsibility."

However, New Hampshire politics have been tightly linked to Public Service Co.'s financial condition.

It was the grass-roots efforts of the Granite State Alliance, a coalition of nuclear opponents, that helped pave the way for the company's current difficulties in financing the Seabrook plant, company officials conceded.

Gov. Meldrim Thomson, Seabrook's strongest ally, was defeated at the polls in large part because he supported CWIP-Construction Work In Progress-a controversial 9 percent surcharge paid by retail customers to help finance the plant.

The CWIP charge produces $18 million annually.

Hugh Gallen was elected governor of one of the nation's fastest growing states -one of the reasons cited for the need for the Seabrook plant-campaigning against Thomson's "sales tax," as he called it, and attacking the company for forcing consumers to bail it out of its financial problems with CWIP.

His election prompted Kidder, Peabody Inc. and Blythe, Eastman, Dillon and Co., New York investment firms underwriting Public Service Co. stock, to postpone the sale of 2 million shares, which had been designed to raise $400 million. The sale date, in light of popular political analysis that Thomson would be re-elected, was set for one week after the Nov. 7 election.

With CWIP, Eugene Meyer of Kidder, Peabody, said, the company's cash flow and earnings per share would have been high enough to allow the go-ahead on the stock sale. Without it, the deal was off.

But the nation's financial community has warmed to the power company in recent days because Public Service Co. intends to replace CWIP with a request for a massive rate increase, according to a source close to the financial negotiations.

"It's the most logical solution next to selling off part of the company's interest in Seabrook," the source said. "Nobody on God's earth is going to get a power supply for nothing."

Most legislative leaders here agree that a bill will be approved this session banning CWIP. The issue would then be dead.

In the meantime, Republican House Majority Leader Marshall French has come up with an alternative called "future credit accounts." It would allow customers to build credit in kilowatt hours or dollars toward a future electric bill after Seabrook is built-sort of a CWIP charge with a payback guarantee.

"Public Service Co. has an awesome responsibility to anticipate our needs and guarantee they can provide the power we will need when we need it," said French. "This is an area where we in the legislature must work co-operatively with PSC; both sides must be willing to work diligently to arrive at a slution that will benefit all citizens by giving them the electricity they will need at a reasonable price."

Responded Democratic House Minority Leader Chris Spirou: "If I didn't know better, I'd think French was elected president of the board of Public Service Co."

Spirou leads the legislative forces who feel no compunction to solve Public Service Co.'s problems. "Nobody told me when I was running for office that I had an obligation to run PSC's business," he said.

"I'm predicting they've not going to close anything down-they'll find a solution. Who are they kidding? PSC is making profits that are going out of space. I'm not buying any of their garbage."