The campaign of independent U.S. Senate candidate Angus King was still not saying Friday whether the wealthy businessman and former governor will release his tax returns.

King’s spokeswoman, Crystal Canney, said Friday evening that the campaign expects to announce its intentions Monday, one week after his two major-party opponents agreed to share their past 10 years’ tax returns with the public.

Cynthia Dill, the Democratic nominee for Maine’s open Senate seat, called on King and Republican Charlie Summers on Monday to join her in releasing their tax returns with the help of a third party. Dill proposed that the release happen on at 5 p.m. Oct. 1.

Summers quickly agreed; King’s campaign has not.

King would face the most scrutiny — and the most political risk — in releasing his tax information. He is still the presumed leader in the race, but his lead over Summers and Dill has shrunk, according to recent polls.

Financial disclosure forms filed with the U.S. Senate clearly show that King is the wealthiest of the three top candidates. He reported earning $256,000 in 2011 and the beginning of 2012, compared with about $35,700 for Dill and about $70,000 for Summers.

Out-of-state Republican political action committees have tried to make King’s wealth an issue. The National Republican Senatorial Committee has claimed that King made “millions” from a wind power project in western Maine.

King’s campaign has angrily disputed any such suggestions — claiming he made $212,000 from the Record Hill project — and has tried to get the ads pulled from television.

Democrats have made tax returns and wealth an issue in the presidential campaign, in pressuring Republican Mitt Romney to release his records. Romney released his 2011 returns and details of past tax records last week.

Dill said that she is merely interested in transparency, although she has used King’s hesitation to strike out at him.

“We all know that he won’t tell Maine voters which party he would caucus with if he were elected to the U.S. Senate,” Dill said earlier this week. “But on this issue of his federal tax returns, can he please give us a ‘yes’ or ‘no’ answer?”

Summers’ campaign said Friday that it welcomes the opportunity, and criticized the King campaign’s delay in signaling whether it will go along with the plan.

“Between taking money from super-lobbyists in D.C., manipulating news stories on his website and now refusing to release his tax returns, how can King continue to tell Mainers with a straight face he’s a different type of politician?” Summers spokesman Drew Brandewie said in a prepared statement.

Kevin Miller — 317-6256

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Twitter: @KevinMillerDC