RICHMOND — The Virginia House of Delegates narrowly approved a proposed constitutional amendment aimed at creating a bipartisan commission to draw political maps, resolving an issue that divided the Democratic majority as time was running out on this year's session.

Friday's contentious 54-to-46 vote came over the objections of several members of the Black Caucus who favored an alternate route for redistricting that they said would better protect the interests of minorities. The debate, which has raged behind the scenes for the past several weeks, aired deep divisions among Democrats.

Supporting the amendment amounted to “the devaluation of the black voices in this chamber,” Del. Lashrecse D. Aird (D-Petersburg), who is African American, warned on Thursday.

“Our 400-year history is replete with our voices being silenced,” Del. Jeffrey M. Bourne (D-Richmond) said Friday, referring to the 1619 landing of the first Africans in bondage in the English colonies.

One pregnant lawmaker — Del. Kelly K. Convirs-Fowler (D-Virginia Beach) — returned from home bed rest to help support the effort to kill the measure. But the vote fell short, with nine Democrats joining all Republicans in supporting the proposed amendment.

Del. Schuyler T. VanValkenburg (D-Henrico) defended the measure, which he had sponsored and which he admitted was “not perfect.” As a high school civics teacher, he said, he had taken care “to make sure I am doing the right thing. . . . I do think it’s a good product. I do think it moves us forward.”

As the legislative session nears its end, scheduled for Saturday, Republican lawmakers had turned up the pressure on Democrats to act on an issue most had trumpeted during last year’s election campaigns. They accused Democrats of faltering in their commitment to nonpartisan redistricting now that they have control of the legislature.

Gov. Ralph Northam (D) also weighed in, suggesting he might call a special session of the General Assembly if the House stalemate continued.

House Democratic leaders who favored scrapping the amendment spent much of Thursday afternoon and Friday morning pressuring a handful of colleagues to abandon it. They pointed out that the proposed amendment does not explicitly prohibit gerrymandering. Del. Marcus B. Simon (D-Fairfax), the party’s parliamentary whiz, offered a substitute proposal that would create a redistricting commission composed entirely of citizens with no legislative members.

Simon said it was intended “to signal to the public what we are trying to accomplish . . . a truly nonpartisan process.”

But the gesture wasn’t enough. It would have taken at least two years to go into effect, missing next year’s redistricting, and failed on a vote of 54 to 46.

The original proposed constitutional amendment was first approved last year when Republicans controlled the legislature, and had to be reenacted this year before the referendum could go to the voters in the fall. Most Democrats supported it the first time around, though members of the Black Caucus objected from the beginning.

The proposal, which has already passed the Senate and does not need Northam’s signature, would set up a bipartisan commission of legislators and citizens to handle the politically charged task of drawing legislative maps. Virginia is set for redistricting next year based on the results of this year’s census.

In the past, the General Assembly drew the maps, letting the party in control tailor legislative and congressional districts to preserve their power. But the most recent effort — in 2011, when Republicans controlled the House and Democrats ran the Senate — faced charges of racial gerrymandering, and the U.S. Supreme Court ordered two separate do-overs.

If voters approve the new system, the bipartisan commission would submit a map to the General Assembly for an up-or-down vote, with no changes permitted. A failure to come up with a map would send the issue over to the Virginia Supreme Court.

Members of the Black Caucus objected to the court’s role, saying most justices are conservatives appointed during a long period of Republican domination in the legislature. They also objected to the lack of language in the amendment specifically protecting the interests of minorities.

“We must be vigilant and adhere to an extraordinarily high standard when proceeding with permanently changing the Constitution,” House Speaker Eileen Filler-Corn (D-Fairfax) said in a statement after Friday’s vote. “In my opinion, this Amendment fails to meet that standard.”

An alternative, sponsored by Del. Marcia S. “Cia” Price (D-Newport News) would have set up the same kind of commission but included language from the federal Voting Rights Act and a different system for resolving stalemates. That route would have been under statute, instead of through the constitution, because there is no time to start another amendment process before next year’s redistricting.

The House approved Price’s bill but had put off acting on the amendment, unable to resolve disagreements within the Democratic caucus.

Speaking during debate on Thursday, Price slammed colleagues who she said had come to her with whispers to say they opposed the amendment but were afraid to act because they’d look like they were wavering on their commitment to end gerrymandering.

Blaming “threats” and “flat-out lies,” Price asked: “Who are we if we bend to that and not to fairness and justice?”