The Virginia Senate killed a contentious measure Monday that would have repealed a requirement that schoolgirls be immunized against a virus linked to cervical cancer before entering the sixth grade.

The General Assembly will most likely not take up the mandate until next year. The state has required the vaccination against the human papillomavirus for five years but allows parents to opt out their children.

The equally divided Senate also postponed debate on other controversial pieces of legislation after it became unclear whether there was sufficient support to approve them.

Those included legislation that would require women to undergo ultrasounds before abortions and another ending tenure protections for public school teachers.

Senate Democrats took credit Monday for the defeat of the HPV repeal.

Meanwhile, Republicans narrowly tightened voting restrictions with a tie-breaking vote by Lt. Gov. Bill Bolling (R), who presides over the Senate.

Democrats complained that the legislation, and similar voter ID bills around the nation, would suppress the votes of minorities, the elderly, students and the poor, who are less likely to have the needed identification.

“This is another day of shame,’’ Sen. Yvonne B. Miller (D-Norfolk) told her colleagues.

The bill requires voters to have some identification at the polls. Those who do not have the documents would vote by provisional ballot but must return to their local registrar with the needed identification.

“That is all this bill does, it discourages fraud,’’ Sen. Mark Obenshain (R-Harrisonburg) said.

With the 60-day legislative session scheduled to end in two weeks, some of the most controversial bills are still making their way through the General Assembly — and emotions are running high.

Proponents of the ultrasound measure and other abortion-related bills gathered on Capitol Square on Monday, holding baby balloons and pink-and-blue signs that said “Mommy, I’m not a blob’’ and “I want to LIVE.” A women’s rights group organized a candlelight vigil outside the governor’s mansion Monday night.

In the House, Del. Robert H. Brink (D-Arlington) shared a letter from business leaders who urged Gov. Robert F. McDonnell (R) and the GOP-led legislature to drop social legislation and instead focus on measures that would boost Virginia’s business-friendly atmosphere.

Deputy House Majority Leader Todd C. Gilbert (R-Shenandoah) countered that social legislation has accounted for a small share of bills this session, and that business leaders are likely more concerned about the state budget, which Senate Democrats are threatening to derail partly in a bid for power-sharing.

The Senate is expected to hold a vote on the ultrasound and teacher tenure bills Tuesday afternoon.

The HPV bill had passed the House this year, and in previous years the legislation had died at the hands of the Democratic-controlled Senate. Those who support lifting the mandate thought they had a better chance at repeal this year because the GOP controls the Senate.

They said parents, not the government, should decide whether girls should be vaccinated. But those who support the requirement said the vaccine would encourage sex among teenagers, because the virus is sexually transmitted.

“The source of this threat is not sex. It is a virus,’’ said Sen. John Edwards (D-Roanoke), whose sister-in-law recently died of HPV. “Whatever we do in this body, we should do based on reason and not based on rigid ideology.”

Sen. Richard Saslaw (D-Fairfax) motioned that legislation be referred back to committee and postponed for the year. A similar move by Saslaw was used last week to defeat legislation that would have given rights to a fertilized egg.

The Senate voted 22 to 17 — with Republican Sens. John Watkins (Chesterfield) and Frank Wagner (Virginia Beach) joining all Democrats — to postpone the legislation until 2013.

Virginia was the first state in the country to mandate that girls receive the vaccine against HPV, which causes genital warts and can cause cervical cancer, after a federal advisory panel suggested routine vaccination for 11- and 12-year-olds in 2006.

After emotional debates in several states since, only the District has followed Virginia and required the vaccination. Both jurisdictions offer opt-out policies that allow parents to decline to have their daughters vaccinated.

HPV vaccination rates in the state are above the national average. About 54 percent of Virginia girls ages 13 to 17 have had at least one dose of the vaccine, compared with 49 percent nationwide, according to the federal Centers for Disease Control and Prevention.

Staff writer Laura Vozzella contributed to this report.