The development is a further twist in the ongoing political crisis in the ex-Soviet state since President Viktor Yushchenko ordered the Supreme Rada to disband April 2 and early elections to be held after accusing the majority coalition of usurping power.
The 14-member Constitutional Court was due to begin examining lawmakers' complaint against the order Wednesday.
"Certain political forces are exerting severe pressure on some judges and the Constitutional Court as a whole," Viktor Shishkin said, adding the judges had requested protection. "Such a situation does not allow us to make a lawful decision."
Shishkin said some senior officials and politicians, pursuing their narrow-interest political goals, had called the decree unconstitutional before a court ruling on the matter, thereby undermining and pressurizing the court.
The judge said the pressure had forced Constitutional Court Chairman Ivan Dombrovskiy to hand in his resignation last week, which, however, was not accepted.
Yanukovych, whose Party of Regions dominates the Supreme Rada, had said Dombrovskiy, also appointed in August under the presidential quota in a power-sharing deal with the premier, would request his resignation well ahead of the announcement.
Earlier Tuesday, a member of pro-presidential bloc Our Ukraine blasted similar assessments of the presidential order from Russia as interference in a sovereign state's affairs.
"A statement made by the State Duma speaker, when he describes the Ukrainian president's decree to dissolve parliament as unconstitutional, should be qualified as interference in an independent state's domestic affairs," Natalia Prokopovych said.
Prokopovych said the Constitutional Court alone had the authority to decide on the legality of the move and condemned what she said were Russia's repeated attempts to influence Kiev's policies, in an apparent reference to Moscow's open backing of Yanukovych in a race against Yushchenko in 2004 and its alleged use of energy supplies as a political tool.
Russia's parliamentary speaker, Boris Gryzlov, called the order unconstitutional and an "infringement on democracy" Tuesday. And another senior Duma member said Russian lawmakers would travel to the ex-Soviet state April 11 to help tackle the crisis in response to an appeal from the Ukrainian parliament Monday.
The current crisis was triggered by the defection of 11 members of Our Ukraine and the opposition Yulia Tymoshenko factions, who joined the ruling coalition and moved it closer to a 300-seat majority with the power to override presidential vetoes and impeach the president.
The Western-leaning Yushchenko and the more Moscow-friendly Yanukovych have so far failed to reach a compromise.
Yushchenko's press office meanwhile said the president would meet with opposition leaders 5:45 p.m. local time (2:45 p.m. GMT) Tuesday to discuss the possibility of forming a coalition in the run-up to a snap election fixed for May 27.
Thousands of coalition supporters have been rallying in Kiev, and opposition forces are preparing to renew protests, bringing back memories of the "orange revolution," which swept Yushchenko to power.
Defense Minister Anatoliy Hrytsenko said after meeting earlier Tuesday with Yushchenko, who reiterated appeals to security bodies to stay out of politics, that a state of emergency or any other tough measures were out of the question.