PORTLAND – Peter Wiley, a longtime Maine political adviser and chief of staff for U.S. Rep. Tom Allen, died unexpectedly Monday.

Wiley, 58, was visiting his father, Harold Wiley, in Florida for the weekend. The cause of death was an apparent heart attack, Allen’s office said.

He served as Gov. Angus King’s chief operating officer and as a member of the state Board of Environmental Protection under Gov. Joseph Brennan.

Contacted Monday afternoon at his Portland office, Allen said he and his staff were still reeling from the news.

Wiley had worked for the five-term congressman a little less than a year, “but he had done an excellent job,” Allen said.

In particular, Allen praised Wiley’s work last year as the state’s congressional delegation united to fight the proposed closing of military installations in Kittery, Brunswick and Limestone.

“He had a lot of relationships” within government, said Allen, whose 1st Congressional District comprises southern and parts of midcoast and central Maine.

“He was a friend. I honestly can’t remember how I first met him,” he said.

Wiley had worked on Allen’s failed gubernatorial bid in 1994, and had worked on former Attorney General Jim Tierney’s unsuccessful campaign for Congress.

Allen spokesman Mark Sullivan said he met Wiley 20 years ago.

“I’d known Peter since I was deputy commissioner of the Department of Conservation and he was chairman of the Board of Environmental Protection back in the mid-’80s,” he said. “He was always just an incredibly effective and inspiring person.”

After working for King, Wiley went to work for the National Governors Association in Washington, D.C., Sullivan said.

“He and his wife just bought a house here in Portland,” Sullivan said.

In a statement, Allen called Wiley “both my valued colleague and dear friend. Peter was a talented, gifted administrator and attorney. I shall always be grateful for his strong, effective leadership of this office.

“Since news of his death began to circulate, our phones have rung off the hook with calls from people whose lives he touched. One adjective – kind – is repeated by all who knew Peter.”

Gov. John Baldacci said in a statement that Wiley “was among the finest gentlemen to ever participate in public service.”

U.S. Sen. Olympia Snowe offered condolences to Wiley’s family, saying he was “an admirable and hard-working man who served Congressman Allen with excellence.”

Wiley is survived by his wife, Betsy, a daughter, Martha, and a granddaughter, Grace.

Details on services or memorials were to be released later.