As Rep. Edward J. Markey (D-Mass.), a national leader of the nuclear freeze movement, sees it, his battle for reelection is a crusade against "special interests."

"There is so much radioactive money in this campaign that it glows in the dark," he said, attacking his opponent's contributions from the nuclear power industry.

Samuel Rotondi, a former state senator who is challenging Markey in a potentially close primary next Tuesday, also sees the race in terms of "special interests," noting Markey's contributions from telecommunications companies.

"Ed has given new meaning to the phrase, 'reach out and touch someone,' " Rotondi said, reminding audiences of Markey's role in telephone industry legislation.

The race in Massachusetts' 7th Congressional District, a swath of medium-sized, working-class towns across the northern part of the state, has unexpectedly tightened in the last few weeks, and the charges and countercharges are symptomatic of the way the financing of congressional elections has become an issue in itself.

Once considered a shoo-in, Markey, a fixture in House debates on defense spending and a critic of the domestic nuclear utility industry, acknowledges that he faces a "very tough race," while claiming his private polls show him 15 points ahead.

Last May, Markey dropped out of the Democratic primary for the seat of Sen. Paul Tsongas (D-Mass.), who is not seeking reelection, at the last minute and dropped back into the 7th district race, giving a bevy of state legislators, who had announced their candidacies, only three hours to meet the state deadline for filing signatures to recapture their statehouse seats.

The move brought heavy criticism. The Boston Globe suggested Markey was "a selfish politician who will go to extraordinary lengths to stay in the plush surroundings of the Capitol."

And, while the Globe endorsed Markey today, it called the choice "difficult."

The Boston Herald and the district's major daily and weekly newspapers have endorsed Rotondi, as have a majority of selectmen and other local officials. Markey has raised $268,000 to date to Rotondi's $310,000, according to both candidates.

Last month, Rotondi challenged Markey to return $33,000 he said Markey has raised from political action committees (PAC) in the telecommunications, television and securities industries that stand to benefit from his seat on a subcommittee which oversees them.

Markey said he stopped accepting PAC money in 1984, and has refused more than $150,000 since January.

The rhetoric escalated Monday when Markey charged that Rotondi has received more than $16,800 in contributions from individuals associated with the nuclear power industry, among them, funds from utility executives in South Carolina, California, Mississippi, Illinois and Michigan.

Rotondi countered that only 5 percent of his contributors and funds are from people connected with the nuclear industry. He charged that two-thirds of Markey's money has come from out of state, including more than $25,000 from executives of telecommunications companies.