Among them was Valery Zorkin, chairman of the Constitutional Court and an important arbiter in a ceaseless power struggle that Mr Yeltsin wants resolved in his favour through the introduction of a new constitution.
While frequently critical of Mr Yeltsin in the past, Mr Zorkin yesterday offered qualified support to a so- called 'presidential' draft that the Kremlin insists must be the sole basis for discussion during the assembly. Attended by more than 700 delegates from Russia's nearly 90 regions and republics, the gathering is the first event of its kind since 1918.
Mr Zorkin said he 'favoured a strong presidential power in Russia because a parliamentary republic is good only if there is a well-developed party system and firmly established pluralism in society,' according to Itar-Tass.
Mr Zorkin was one of some 50 delegates who walked out of the assembly's opening session on Saturday in protest at what he termed a 'disgraceful spectacle'. The convention sank into turmoil after President Yeltsin huffily refused to let the parliamentary leader, Ruslan Khasbulatov, speak and Kremlin security guards dragged a Communist delegate from the hall screaming. Mr Yeltsin's supporters condemned the incidents as a deliberate provocation.
By yesterday tempers had cooled, though Mr Khasbulatov did not return and was reported by Itar-Tass to be meeting legislative leaders behind closed doors. Alexander Kotenkov, a presidential legal adviser, said delegates had 'screamed their lungs full' and could now meet a deadline of 16 June fixed by Mr Yeltsin for a final text. Vladimir Shumeiko, a deputy prime minister, said 80 per cent of delegates would back Mr Yeltsin's draft, which sharply expands the powers of the executive and cuts back those of the legislature.
Also back in the Kremlin yesterday was Oleg Rumyantsev, author of a rival draft which, though initially sponsored by Mr Yeltsin, is now supported by his foes in parliament.
Mr Yeltsin gained a further boost from signs of a growing split in the the largest opposition grouping, Civic Union, a centrist coalition whose leaders include the rebellious Vice President, Alexander Rutskoi.
One of the group's main components, Nikolai Travkin's Democratic Party of Russia, pulled out of the alliance because of alarm over Mr Rutskoi's venomous tone and drift into the hardliners' camp.
Mr Yeltsin, after months on the defensive, seized back the initiative with his referendum victory on 25 April. He now needs to introduce a constitution to sweep away rules written for Brezhnev in 1978 which are loaded with ambiguity and contradiction.