WASHINGTON — Representative Joseph P. Kennedy III was frustrated as he sat in his Capitol Hill office last week.
Preparing for a flurry of final votes to end the session for the year, he was thinking about a vote the House and the Senate failed to take: whether to authorize the 3½-month war against the Islamic State in Iraq and Syria.
“What are we trying to do? What does success look like? How long is it going to take?” Kennedy, a member of the Foreign Affairs Committee, asked in an interview. “How much is it going to cost? What are we asking our men in uniform and their families to bear? Those basic, fundamental questions weren’t answered.”
Kennedy’s vexation at the lack of congressional debate on what he called “another military conflict in another Middle Eastern country mired in yet another civil war” was aired by other members of the Massachusetts congressional delegation who are assigned to key committees with oversight of foreign policy and the military.
They expressed some hope that when the new Congress convenes in January — with Republican control of the House as well as the Senate — that congressional leaders will make it a priority. But they do not have high confidence it will happen.
President Obama has said he would welcome authorization from Congress for the mission but has not formally asked for it.
The US-led air war against the Islamic extremist group that has seized nearly a third of Iraq’s territory and also large parts of neighboring Syria began Aug. 7 — first in Iraq and then, in late September, against targets inside Syria. More than 4,000 airstrikes have been launched and the mission has cost an estimated $1 billion so far, or about $8.1 million a day, according to the Pentagon.
The United States has also enlisted a number of allied militaries in the effort, including four Arab nations. But the majority of strike missions — as much as 75 percent — have been performed by US Navy and Air Force fighters jets, bombers, and remotely piloted aircraft, according to recent military data.
Obama has pledged that he will not dispatch US troops to engage in ground combat; the Iraqi military, along with moderate elements inside Syria, will be trained and outfitted with US arms to fight the group, which is also known by the acronyms ISIS and ISIL.
But the number of US military advisers in Iraq has grown to more than 3,000. Allied nations have agreed to send 1,500 more.
The growing contingent has raised new concerns that the US commitment, which administration officials attest could last years, will steadily grow.
Representative Niki Tsongas, Democrat of Lowell and a member of the Armed Services Committee, worries about the potential that American ground troops will be inserted into the fight.
Recent comments by Secretary of State John F. Kerry and top military commanders that ground combat cannot be ruled out have “raised a lot of alarm bells,” she said in an interview.
“There are still a lot of questions about what the regional partners are willing to contribute,” she added, referring to the Arab members of the coalition. “How much responsibility are they are really going to take on?”
There was an 11th-hour attempt in the Senate to take up the issue last week when the Foreign Relations Committee approved a measure to authorize the operation for three years but prohibited the use of ground troops in combat.
Senator Edward J. Markey, a member of the foreign relations panel who voted in favor of the measure, called the vote a “first step” but acknowledged the end of the legislative session renders it moot.
“We need to have each member be put on record,” Markey said in an interview. “Some want to give the president carte blanche authority to do whatever he wants, including combat troops on the ground, which I oppose. There is a debate of how long the authorization should last — one year, three years, or indefinite. There is a debate over where the authorization should authorize military activity to take place. Just Syria and Iraq? Or anywhere that ISIL may pop up?”
Tsongas said another key question is how it will be paid for.
“In other conflicts, we’ve borrowed our way through it,” she said.
Kennedy even questions whether the Islamic State poses such a dire threat to the United States that it requires another US-led war.
“Is ISIS’s goal there to draw the United States into a conflict to then use that as a way to draw more foreign fighters . . . to expand that conflict?” he wondered. “That is one of the pivot points that should be discussed.”
The leading antiwar voice in the Massachusetts delegation, Representative Jim McGovern of Worcester, said if Congress fails to take up the issue next year, he will use his power to introduce a “privileged resolution” to force a vote in the House.
Correction: An earlier version of this story misspelled the name of Representative Niki Tsongas.