A Texas prosecutor who is leading an investigation into possible illegal campaign spending lashed out at congressional Republicans on Tuesday for changing their rules in order to protect House Majority Leader Tom DeLay (search).

The House Republicans repealed a rule that automatically required party leaders or committee chairmen to step down if they are indicted on a felony charge. The new rule provides for a case-by-case review.

The change means DeLay could maintain his power if indicted in the investigation being conducted by Travis County District Attorney Ronnie Earle.

"Politicians in Congress are responsible for the leaders they choose. Their choices reflect their moral values," Earle wrote in an opinion piece published Tuesday in The New York Times. "The cynical destruction of moral values at the top makes it hard for law enforcement to do its job."

Earle has not said that DeLay is a target, but three of DeLay's top lieutenants have been indicted.

Republicans have accused Earle, a Democrat, of using the investigation as a partisan witch hunt or fishing expedition.

The investigation centers on the use of corporate campaign contributions, long outlawed in Texas, to help secure a Republican majority in the state Legislature in the 2002 election. The corporate donations were made to Texans for a Republican Majority, a political action committee created with help from DeLay.

"It is a rare day when members of the United States Congress try to read the minds of the members of a grand jury in Travis County, Texas. Apparently Tom DeLay's colleagues expect him to be indicted," Earle wrote.

A spokesman in DeLay's office did not immediately return calls seeking comment.