WASHINGTON — Senator Edward J. Markey, who has faced criticism for wavering on how to respond to Syria, said Tuesday that he opposes the current Senate resolution to attack the country because “it is too broad, the effects of a strike are too unpredictable, and because I believe we must give diplomatic measures that could avoid military action a chance to work.”
Markey’s position has been the source of broad interest, and intense lobbying from President Obama and top administration officials, because he occupies Secretary of State John F. Kerry’s former Senate seat and because last week he was the only member of the Senate Foreign Relations Committee to vote “present” on a resolution to use force.
The resolution passed Sept. 4 on a 10-7 vote. Markey said at the time that he did not have enough information to cast a vote; none of the other senators made that complaint.
But the Massachusetts Democrat’s opposition to the current resolution may not matter now, as the Senate on Monday night postponed a vote to close debate on the authorization for force while the Obama administration pursues diplomatic options to removing chemical weapons from the Syrian regime.
Other lawmakers have been crafting alternative resolutions that give the Syrian government time to turn over its chemical weapons under the threat of force. But in an interview Tuesday, Markey would not say whether he would support such a resolution until he saw something in writing. He declined multiple opportunities to set his own parameters or say whether there were any circumstances under which he would vote to authorize force.
Markey said he spent three hours reading classified documents and questioning Senate committee specialists in the morning following his “present” vote on Sept. 4.
He then consulted national specialists over the course of the week, he said. He also spoke three times with Kerry, for 30 minutes with Obama on Sunday, and then for 90 minutes with Vice President Joe Biden on Monday night, one of two conversations with Biden, he said.
Markey said the administration made the same case to him that it has made publicly, but he was not persuaded.
Markey said Kerry did not bring up the men’s longtime friendship or the political debt Markey owes Kerry for helping him gain support for his Senate bid earlier this year.
“It was strictly the issue,” Markey said. “It’s a very great responsibility to have a vote that calls for the use of force and calls for the overturn of a regime in another country, and so each of us has to weigh the question ourselves.”
Markey said he was chiefly concerned with a late amendment to the resolution that supported regime change, even though Obama has said repeatedly that the strikes were not part of a plan to oust Assad.
Markey said Kerry understands his role and he praised Kerry for “an absolutely historically great job” in handling the foreign policy crisis.
Markey’s decision not to support the measure could be embarrassing for Kerry, who for nearly three decades held the Senate seat that Markey now occupies.
While Markey said he is convinced of the evidence that Syria used chemical weapons, he said he remains haunted by Iraq, where he came to regret his vote to authorize force when he served in the House.
“After Afghanistan, after Iraq, after Libya, the American people have a right to know the level of American involvement,” Markey said.
No one in the Massachusetts delegation has spoken publicly in favor of the initial resolution. As the issue has consumed Capitol Hill and the nation, Markey’s colleague in the Senate, Democrat Elizabeth Warren, has declined Globe requests for interviews since Friday.
As of early Tuesday evening, she had not said how she would vote on a resolution to use force in Syria.
Representative Niki Tsongas said in a statement Tuesday that she would oppose the use of force “if a vote were held today.”
“I continue to have very grave concerns about the efficacy of proposed US military action in Syria and its consequences,” the Lowell Democrat said.Noah Bierman can be reached at email@example.com. Follow him on Twitter @noahbierman. Staff writer Matt Viser contributed to this report.