The parliament was adjourned after the vote, making it impossible for the president to formally nominate a new prosecutor.
MPs from the Party of Regions, led by Yushchenko's rival Prime Minister Viktor Yanukovych, threatened to prevent Viktor Shemchuk, Piskun's former deputy and chief prosecutor of the Crimea, whom Yushchenko had appointed as Acting Prosecutor General, from entering the Prosecutor General's Office.
"Even if the court of appeal rules that Piskun was [rightly] dismissed as Prosecutor General, we will physically prevent Shemchuk from entering the office because the president must have a Rada stamp of approval before going ahead with the dismissal," Vasyl Kiselev, a senior MP with the Party of Regions, said outside the Prosecutor General's Office.
"The law is on our side. If the president does not understand this, we will try to convince him that he should not break the law and the Constitution," he added.
Both contenders for the prosecutorial post described the situation as beyond reason.
"So far, I am [the Prosecutor General]. We'll wait and see," Piskun said. "The decree [to appoint Shemchuk] is outright nonsense."
Shemchuk said he could as well serve as Prosecutor General outside his office but said, "this looks absurd to me."
Yushchenko has been pressing for parliament's dissolution and early elections since April 2, when he ordered parliament dissolved following the defection of 11 opposition members to the premier-led ruling coalition in parliament, which the president said violated the Constitution.