The House Judiciary Committee voted 20-14 on Wednesday to approve a contempt of Congress resolution against former senior White House aide Karl Rove.

The panel voted along party lines.

Rove refused to comply with a committee subpoena to appear at a July 10 committee hearing to testify about allegations that the Justice Department had engaged in politically motivated prosecutions of Democratic officials, including former Alabama Gov. Donald Siegelman.

Rove’s attorney cited executive privilege.

“It’s regrettable, but it has become necessary to pursue this course because we have been left with no other option,” Judiciary Chairman John Conyers Jr., D-Mich., said. Conyers called Rove’s refusal to appear a “grave challenge to the authority of the Judiciary committee.”

Rove denied any involvement in the matter in a July 22 letter to Lamar Smith of Texas, the top Republican on the panel. Rove has offered to submit to an off-the-record, untranscribed interview or to answer written questions about the Siegelman case, but not about the broader issue of the politicization of the Justice Department. Conyers rejected that offer.

Smith said Wednesday that there is no “credible evidence” to support the resolution. Smith said the committee was opening “the curtain on its version of a Salem witch trial of Karl Rove.”

The practical effect of a contempt resolution is likely to be limited, even if the full House votes to approve it. In February, Attorney General Michael B. Mukasey refused to refer a contempt of Congress citation against President Bush’s chief of staff, Joshua B. Bolten, and Harriet Miers, a former White House counsel, to a federal grand jury, as required by law.

The House had voted to cite Bolten and Miers for contempt after they refused to comply, on executive privilege grounds, with Judiciary subpoenas related to the firings of nine U.S. attorneys in 2006.