Opposition deputies block the speaker’s rostrum during a session of the Ukrainian parliament in Kiev on Thursday. The Ukrainian government issued an order saying it intended to renew active dialogue with Russia as it suspended preparations for concluding an association agreement with the European Union. (REUTERS)

Stuck between Russia and the European Union, and chafing at the need to choose between them , the Ukrainian government faltered Thursday as threats from its big Slavic neighbor mounted.

The cabinet suspended Ukraine’s preparations to sign an “association agreement” with the E.U. next Friday — after spending all year declaring its intention to do so and ushering through the parliament a packet of laws aimed at helping it meet the 28-member bloc’s expectations.

Part of the dilemma it faced is homegrown, involving the fate of Yulia Tymoshenko, the imprisoned former prime minister whose release Europe insists on. The other part has to do with Moscow.

Russia bullied Ukraine all summer long, with threats, customs slowdowns at the border and sanitation-related sanctions on chocolates and other imports — all of which at the time seemed to strengthen Ukraine’s resolve to turn westward to its European neighbors.

But more recently, top Russian officials have quietly made it clear that doing so would cost the fragile Ukrainian economy dearly. Ukraine conducts a large part of its trade with Russia, and the consequences of Russian obstruction would be painful. Ukraine has said it could make do without Russian natural gas, but a moratorium on gas purchases that it implemented last week quickly crumbled.

If Kiev carries through with Thursday’s decision, it would be a substantial blow to the E.U.’s “Eastern Partnership” program, although Moldova and Georgia are expected to sign on as associates next week.

But the Tymoshenko case colors all of President Viktor Yanukovych’s calculations. His bitter rivalry with her and the prosecution of her and her allies as soon as he took office have come to define Ukrainian politics, and he has staunchly resisted pleas for her release.

In recent months, a resolution seemed possible. But Thursday, the parliament failed to pass any of six bills that would have enabled Tymo­shenko to leave Ukraine for medical treatment abroad, with Yanukovych’s Party of Regions and the Communists withholding their support.

E.U. representatives have repeatedly declared that Ukraine cannot sign on to the partnership program as long as it practices “selective justice” and have warned Yanukovych that Europe is not bluffing about the necessity of Tymo­shenko’s release.

Alexei Pushkov, a member of the Russian parliament’s foreign affairs committee, sent out a string of triumphant tweets Thursday. He said that the E.U. had pushed Ukraine too far and that the effort had been a “major miscalculation.”

But with a week to go, there is plenty of time for either side to blink.

Yanukovych was in Vienna on Thursday and said Ukraine would continue to work toward integration with Europe. In Kiev, some politicians said Ukraine should offer itself as a bridge between the E.U. and the Customs Union of Russia, Belarus and Kazakhstan that Russian President Vladimir Putin is determined to expand.

But at a recent conference in Yalta, Western officials made it clear that eventually Ukraine has to choose.

The European option could hurt the country’s economy in the short run, but polls show that it is popular even in the Russian-speaking regions of eastern Ukraine. The oligarchs who run the economy — and whose relations with Yanukovych might be described as complicated — are leery of Russian takeovers if Ukraine joins the Customs Union and have been looking forward to the respectability of ties with the West.

Kiev’s hesi­ta­tion does not mean that the government has totally pulled the plug on the E.U. agreement, Andriy Honcharuk, an adviser to Yanukovych, said Thursday. “No, this is not the plug,” he told reporters in Vienna. “This is just a formulation of the question. Consultations are ahead.”

The decision also does not mean that Ukraine will immediately join Putin’s Customs Union. Yanu­kovych clearly wants to keep his options open as long as he can.

The E.U. has offered Ukraine lower tariffs and direct financial assistance if it signs the association agreement. But Ukrainians understand that there is no promise of membership anytime soon.

Putin, on the other hand, is holding out the prospect of full membership in the Customs Union and going on at length about the Slavic culture that connects the two nations. But to join him would mean putting the lid on Ukraine’s European aspirations, after 20 years of hoping — with incalculable political consequences at home.