RICHMOND, Va. — Virginia Republican Del. Bob Marshall says it’s his duty to try and pursue impeachment proceedings against Attorney General Mark Herring.

A handful of African-American ministers joined Marshall on Tuesday at a news conference in Richmond to denounce Herring’s decision to back two same-sex couples challenging state laws. They also criticized Herring’s opposition to a constitutional provision barring gay marriage in Virginia.

The ministers said Herring had misled them about his views on same-sex marriage when he was a candidate for office.

A spokesman for Herring called Marshall’s news conference a “desperate ploy.”

Marshall is the General Assembly’s most outspoken social conservative, and co-authored the state’s 2006 constitutional amendment banning same-sex marriage. The ban was struck down by a federal judge earlier this year.

He wants a House of Delegates committee to investigate whether Herring should be impeached for violating his oath of office.

House Republicans leaders have said they do not support Marshall’s effort.

Associated Press contributed to this report.