WASHINGTON, Jan. 19 — The new chairman of the Senate Intelligence Committee on Friday sharply criticized the Bush administration’s increasingly combative stance toward Iran, saying that White House efforts to portray it as a growing threat are uncomfortably reminiscent of rhetoric about Iraq before the American invasion of 2003.   

Senator John D. Rockefeller IV, the West Virginia Democrat who took control of the committee this month, said that the administration was building a case against Tehran even as American intelligence agencies still know little about either Iran’s internal dynamics or its intentions in the Middle East.

“To be quite honest, I’m a little concerned that it’s Iraq again,” Senator Rockefeller said during an interview in his office. “This whole concept of moving against Iran is bizarre.”

Mr. Rockefeller was biting in his criticism of how President Bush has dealt with the threat of Islamic radicalism since the Sept. 11 attacks, saying he believed that the campaign against international terrorism was “still a mystery” to the president.