By Thomas Grove

KIEV (Reuters) - Student Taras Zagorbenskyy jumped on a bus from western Ukraine as soon as he saw on a social networking site that others were gathering in Kiev to protest President Viktor Yanukovich's walking away from a landmark deal with the European Union.

He is among several thousand protesters, many of them students, drinking tea and keeping warm around fires in oil barrels in the capital's main square.

The demonstrations have evoked memories of the 2004-5 Orange Revolution when hundreds of thousands, led by now jailed opposition leader Yulia Tymoshenko, gathered in the same square to thwart Yanukovich's first bid for the presidency.

The protests against the government's decision last week to suspend preparations for signing a trade deal with the EU and renew closer economic ties with Russia instead are much smaller and so far no leader has emerged.

But those camped out in the main square say more could still turn up and with internet and social media helping them to organize in the absence of a leader.

"We've been hearing about the European Union for years now, that's all I can remember them talking about. Imagine this is how we saw our future. If he doesn't sign it, there will be a storm of protests," said Zagorbenskyy, 18 from Lviv, a town on the border with Poland.

Ukraine often finds itself at the centre of an East-West tug-of-war and the trade deal, due to be signed in Vilnius, would have marked a definitive turn towards the West.

The protesters, and other critics including EU leaders, were upset by Yanukovich's decision, fearing that Ukraine would swing back into Russia's sphere of influence.

Medical student, Vitali Andres, took 15 hours to drive the 600 kilometers from Lviv because he was stopped several times.

"Police stopped us four times on the way to Kiev, once we were waiting for four hours. They even tried to take our license plate at one point. It was utterly ridiculous," he said.

The arrival of students from outside the capital was an important moment in the Orange Revolution, and although the numbers this time are much lower, their arrival has helped the protests keep momentum.

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"The protests of the Orange Revolution and the current ones have different social implications - then it was a protest of expectations for the better, but today it is a protest over hope that (authorities) want to steal," said Volodimyr Fesenko, analyst from Kiev-based Penta think tank.

ELECTION REHEARSAL

In 2004-2005 Internet access in Ukraine was limited. Tymoshenko, whose imprisonment for abuse of power in 2011 has been a main sticking point in EU talks, rallied her supporters through speeches to the large crowds in Kiev's Independence Square.

Now protesters can easily organize themselves on chat pages or social media. As dusk fell, Zagorbenskyy and his friends were scrolling through Facebook on his smart phone to find the page Kyiv Host, where residents sympathetic to the protest post offers of a bed and perhaps a hot meal.

"We can take in two to three young people in a room... Hot shower, internet access, but you must have your own sleeping bag," wrote a Facebook user with the name Vira Kriv.

But this time around, students have largely avoided representatives of the main political parties which have moved through the city with party flags.

Opposition party leaders are more focused on the 2015 presidential poll, hoping they can galvanize voters using the disappointment over Yanukovich's about face on the EU as well as drawing on popular grievances over corruption in the judiciary and the police force.

"The opposition does not see the protest as a fateful event, but sees it more likely as a rehearsal for the 2015 elections," said Fesenko.

While former boxer Vitaly Klitschko has cut a powerful figure in Ukrainian politics since bursting onto the political scene with his party Udar or "punch", none of the opposition leaders have sought to lead the protests.

Party leaders are likely keen to avoid the example set by former President Viktor Yushchenko, who rode the Orange Revolution to power, but nearly a decade later is reviled for failing to keep his promises then of European integration.

"During the Orange Revolution, there was a belief in the mission that the person we believed in would come to power and everything would be fixed. But we realized it's not about people but about the system," Alexander Kovalyov, 48, a former bureaucrat.

"We've come to believe in ourselves."

Nonetheless, parties have been keen to identify with the protests and party supporters of Udar, Batkivshchyna and the far right nationalist Svoboda or "Freedom" Party handed out Ukrainian flags and distributed food and tea to protesters.

"The people are the power here and they will be the ones to decide whether or not Ukraine gets into the European Union and they will be the ones to decide whether Yanukovich stays in power or not," Sofia Fondarenko, a middle school teacher.

(Additional reporting by Pavel Polityuk; editing by Anna Willard)