The balance in the internal White House debate over Iran has shifted back in favour of military action before President George Bush leaves office in 18 months, the Guardian has learned.

The shift follows an internal review involving the White House, the Pentagon and the state department over the last month. Although the Bush administration is in deep trouble over Iraq, it remains focused on Iran. A well-placed source in Washington said: "Bush is not going to leave office with Iran still in limbo."