▶ Watch Video: Biden to withdraw U.S. troops from Afghanistan by September 11, 2021

Lawmakers are divided on President Biden’s proposal to withdraw U.S. troops from Afghanistan by September, and the differences in opinion do not fall neatly along party lines. The president will announce Wednesday his plan to remove military forces by September 11, 2021, the 20th anniversary of the terrorist attacks at the World Trade Center in New York City and the Pentagon.

“It’s refreshing to have a thought-out plan with a set timetable,” Senate Majority Leader Chuck Schumer said in an interview on CNN Wednesday. “I think the president’s plan is a very good one.”

In a speech on the Senate floor Wednesday morning, Schumer said it is time to end America’s longest conflict “after sinking two decades of blood and treasure into wars in the Middle East.”

“In my view, President Biden’s plan to bring American troops home from Afghanistan is a very wise one,” Schumer said. He also contrasted Mr. Biden’s plan with former President Trump’s plan, whose administration had previously negotiated with the Taliban a complete U.S. troop withdrawal from Afghanistan by May 1, a decision which members of his own party criticized.

“This is a careful and thought out plan with a real timetable and a firm end date,” Schumer said, adding that he had been assured by the White House that “the September 11 date will stick and that President Biden will not kick the can down the road.” Schumer also announced there will be an all-senators briefing from the Biden administration on the drawdown in Afghanistan.

Several progressive members of Congress also applauded Mr. Biden’s decision. Senator Bernie Sanders, an independent who caucuses with Democrats, said in a statement that Mr. Biden was making “the brave and right decision.” In a statement on Tuesday, Democratic Senator Elizabeth Warren said a withdrawal was long overdue.

“While our withdrawal comes years late, President Biden recognizes the reality that our continued presence there does not make the US or the world safer,” Warren said.

In the House, Democratic Congressman Ro Khanna, a prominent progressive, also praised the decision. “I applaud President Biden for achieving an impossibility here in Washington: ending a forever war,” he said.

In a speech on the Senate floor a few moments after Schumer spoke, Senate Minority Leader Mitch McConnell slammed Mr. Biden’s plan, saying the administration is “surrendering leverage.” He argued that withdrawing US forces is “gift wrapping the country and handing it right back” to America’s adversaries.

“The American people need and they deserve a foreign policy that puts our security, our partners and our interests ahead of the reflexive desire to break with the past four years at any cost,” McConnell said.

GOP Senator Jim Inhofe on Tuesday called Mr. Biden’s decision “outrageous,” and Senator Joni Ernst said it was “concerning.” Senator Lindsey Graham, a hawk who occasionally clashed with Mr. Trump on foreign policy issues, said withdrawing troops “canceled an insurance policy against another 9/11.”

Republican Congressman Michael McCaul, the ranking member of the House Foreign Affairs committee, said he was “shocked and extremely concerned” by reports of Mr. Biden’s decision.

“This premature withdrawal shows a complete disregard for the realities on the ground, and will not only put Afghans at risk, but endanger the lives of U.S. citizens at home and abroad,” McCaul said in a statement Tuesday.

But disagreements on the plan aren’t split along party lines, with Democrats universally in favor and Republicans universally opposed. Some Democrats expressed concerns about withdrawing from Afghanistan, and a few Republicans praised Mr. Biden’s decision.

GOP Senator Ted Cruz said Tuesday he was “glad the troops are coming home.”

“Bringing our troops home should not be taken as a sign that America will be any less vigilant in protecting American lives and those of our allies, but we can do so without a permanent military presence in a hostile terrain,” Cruz told reporters.

But Democratic Senator Jeanne Shaheen tweeted she was “very disappointed” in the decision, arguing it “undermines our commitment to the Afghan people, particularly Afghan women.”

Democratic Senator Bob Menendez, the chair of the Foreign Relations Committee, told reporters on Tuesday that he wants “to hear the administration’s rationale” for pulling out of Afghanistan.

“I just am concerned that after so much blood and national treasure that we don’t lose what we were seeking to achieve,” Menendez said. He added he will “certainly will not be supportive of any assistance to Afghanistan if there is backsliding on civil society [and] the rights that women have achieved.”

Democratic Senator Jack Reed expressed unease over the decision, saying the U.S. must “maintain a presence for regional stability.”

“This should be seen as transitional, not as closure,” Reed said.