Allahpundit rounds up reports that indicate the clash between Mousavi and Khamanei could come to a head tomorrow. There's a lot of chatter that Khamanei will call in the Revolutionary Guard, and the Times (UK) reports:
The moderate Iranian leader who says that he was robbed of victory in last week's presidential election faces a fateful choice today: support the regime or be cast out.
Ayatollah Ali Khamenei, Iran's Supreme Leader, has told Mir Hossein Mousavi to stand beside him as he uses Friday prayers at Tehran University to call for national unity. An army of Basiji - Islamic volunteer militiamen - is also expected to be bussed in to support the Supreme Leader.
The demand was made at a meeting this week with representatives of all three candidates who claim that the poll was rigged, and it puts Mr Mousavi on the spotâ€¦
It was unclear last night what he would do or even whether the protests would die away if he backed down.
An hour ago, Mousavi reportedly broadcast his decision on Twitter: "Mousavi & Karoubi ask supporters NOT to attend Friday prayers (which is being delivered by supreme leader Ayatollah Khamenei)."