Update, 4:10 p.m.:. The House of Delegates voted Wednesday afternoon to amend the bill to say that no woman will have to undergo a internal ultrasound involuntarily, and that only an external ultrasounds will be required to satisfy the requirements to determine gestational age.

Original Post: House Republican leaders are expected Wednesday to try to amend a bill that would require women to undergo an ultrasound before an abortion.

Legislators and governor’s staff met Tuesday night to hash out a compromise that would make the ultrasounds voluntary, several people with knowledge of the meeting said Wednesday.

Del. Kathy Byron (R-Campbell), who introduced the bill in the House, said Wednesday that she had not seen the amendment’s language yet and does not know if she will support it.

Democrats asked the bill be re-referred to committee, which would have likely killed it, but the House voted against that along party lines.

“With every day that goes by there is another problem identified with this bill,’’ House Minority Leader David Toscano (D-Charlottesville) said.

Legislators were given copies of a letter from the American Council of Physicians Virginia chapter, which boasts 3,000 physician members, who called on Gov. Bob McDonnell to veto the bill.

But Del. Bob Marshall, a supporter of the bill and author of the so-called personhood bill, chastised his colleagues for letting the media change their mind on ultrasounds.

“Instead of confronting the misinformation that’s going on here, some Republicans want to back away from this,’’ he said. “Instead of confronting the public with the truth, the whole truth and nothing but the truth, we — the descendents of those who fought the British empire — are sounding the call for retreat.”

The Tuesday night meeting took place in the governor’s office in the Patrick Henry Building on Capitol Square, and included the governor’s chief of staff Martin Kent, Secretary of Health Bill Hazel and Dels. David Albo, Todd Gilbert, Rob Bell and Byron, several people with knowledge of the meeting said. They were not allowed to speak publicly about the gathering.

Albo said he was told by legislative leaders not to speak about the meeting or even acknowledge who attended.

The Washington Post reported Wednesday that McDonnell (R) is backing off his unconditional support the bill. Until last weekend, McDonnell and his aides had said the governor would sign the measure if it made it to his desk. McDonnell changed his stance a few days ago.

McDonnell, who held a news conference on a unrelated matter Wednesday, declined to answer reporters’ questions about the ultrasound legislation or Tuesday night’s meeting.

“You know what I’m concerned about? I’m concerned about the budget,’’ McDonnell said as he walked away with security and aides.

The meeting took place after the governor and legislators learned that the ultrasounds could be more invasive than first thought, according to two officials who were aware of the meeting but not authorized to speak about it publicly.

The House and Senate have approved their versions of the bill. On Tuesday, the House postponed a final vote on the legislation— as well as votes on other measures on guns and adoption — for the second day in a row.

Opponents of the measure turned over petitions with 33,000 signatures to the governor’s office Wednesday morning and are planning a rally on Thursday.