The dismantling of three barricades near the building came after opposition leader Viktor Yushchenko began his presidential campaign following two weeks of protests against electoral fraud in the Nov. 21 presidential runoff.
Opposition leaders said the barricades, which prevented senior civil servants from reaching their offices, were no longer necessary and that the real fight now was the campaign for the revote of the runoff election, set for Dec. 26.
By midday Thursday, demonstrators who had kept their vigil round the clock in freezing temperatures simply melted away, although tent camps they had set up near Kiev's main Independence Square remained in place.
Other supporters spent the morning packing and preparing to leave the capital after a night of celebrations following parliament's vote. Yushchenko's campaign staff began organizing an orderly departure for those wanting to return home.
"This is a sad and happy day at the same time," said Oleksiy, a protester from the city of Rivne who gave only his first name. He still had his "Barricade Security" badge pinned to his coat.
"We endured more than two weeks and now we are leaving, but we are leaving as winners," he said, packing his belongings near his tent only yards away from the main government building.
Yushchenko's orange flags and banners reading "We are plenty! We will persevere!" lay abandoned on a muddy embankment in the park overlooking the government building. Garbage collectors removed debris.
A blockade near the president's office remained in place, but Roman Zvarych, a member of Yushchenko's campaign staff, said he believed it, too, would be removed.
"I don't believe we should keep the blockade of the presidential administration, because it's only one person that matters now and that is the president," he said, referring to outgoing President Leonid Kuchma. "Maybe we will only block his car from now on."
Yushchenko said the peaceful protests, dubbed the "Orange Revolution," managed to cancel the fraud-tainted victory of Prime Minister Viktor Yanukovych in the presidential runoff and press home legal changes to avert the rerun from being rigged.
"During these 17 days we have gotten a new country," Yushchenko told roaring throngs of supporters in Independence Square on Wednesday. "We have realized that we are a European nation."
Wednesday's surprise parliamentary vote endorsed a compromise package that called for electoral reform in exchange for a reduction in presidential powers.
Yushchenko said the Kuchma-endorsed electoral amendments place tight restrictions on absentee and home voting. The reforms ensure opposition members are represented in local election commissions in equal numbers as opponents.
In his speech, Yushchenko also pledged to maintain warm relations with Ukraine's neighbors, including Russia.
Russian President Vladimir Putin has staunchly backed Yanukovych and congratulated him on winning the Nov. 21 vote while the opposition and the West charged fraud.
In Moscow, a person close to Putin's administration said Thursday on condition of anonymity that the Kremlin was pleased about the agreement on reforms diluting the power of the presidency, saying it would give Russia more of a chance to influence Ukrainian policy.
Russian politicians have expressed fear that Yushchenko would pull Ukraine westward, out of Russia's orbit.
Yushchenko has urged his supporters to focus on campaigning for the next ballot against Yanukovych, encouraging demonstrators to join local election commissions and become ballot monitors.
Yushchenko emerged from the 17-day political crisis a winner, succeeding in his demand for a rerun ballot without his supporters resorting to violence. But Kuchma, who backed Yanukovych, can also claim victory because he succeeded in trimming his successor's powers.
"I am confident of victory on Dec. 26," Yushchenko said in a speech that ended with fireworks streaking over the frigid Ukrainian capital.
Under the parliamentary changes, the president no longer has the power to appoint his own government, but keeps the right to reject parliamentary nominees for the top three positions — prime minister, foreign minister and defense minister. Parliament also earns the right to appoint all other Cabinet positions without presidential approval.
Campaigning in eastern Ukraine, Yanukovych said the decision was "made under pressure" and described it as a "soft coup d'etat."