Following a lengthy six-hour debate, Czech senators approved the treaty by a margin of 54-20, a considerable majority given that the Lisbon Treaty has long been a highly divisive 'hot potato' in Czech politics.
Outgoing Czech Prime Minister Mirek Topolánek, in one of his last acts as head of government, was central to the outcome of the vote, pleading with members of his ODS (Civic Democratic) Party to prevent another "shameful moment" after the cabinet's "shameful fall midway through the EU presidency".
Topolánek's success in pushing the treaty through the Senate can be considered a "significant achievement" for the outgoing PM, political analysts told EurActiv.
Klaus: Will he sign?
Final ratification of the treaty now depends on Czech President Václav Klaus, whose assent and signature is required to pass Lisbon into law. Klaus, a long-time opponent of the treaty, previously indicated he would not approve the treaty before Ireland's second referendum later this year.
Technically, the treaty has not been ratified in Germany or Poland either. Polish President Lech Kaczyński, another prominent Eurosceptic, has maintained that he too will not sign the treaty until it has been passed in Ireland, despite the Polish parliament's approval of the text in April 2008.
In Germany, meanwhile, a judgement from the Constitutional Court on the treaty's compatibility with German law is expected this summer.
German Socialist MEP Jo Leinen, who chairs the European Parliament's constitutional affairs committee, told EurActiv that the Czech vote was an "important breakthrough", and indicated his belief that Germany would soon follow suit, most likely in June following the European elections.
"No-one in Germany thinks our constitution is not compatible with the treaty," he said, explaining that the Constitutional Court may issue some "interpretations and guidelines" for how the country's internal rules implement EU legislation.
"I am now very optimistic that we could have this treaty by the end of the year," he concluded.
All roads lead to Ireland
The EU spotlight will therefore return to Ireland, where a second referendum is expected in the autumn. Irish European Affairs Minister Dick Roche told EurActiv that the Czech vote was "excellent news", and argued it was "good for Europe that 26 countries have now ratified by parliamentary majority".
He confirmed that the second referendum would "most likely be held in the autumn," following clarification of Ireland's legal guarantees at an EU summit in June.
Roche said that the Czech result could be an "influencing factor" on the Irish referendum. Recent polling has indicated a strong swing towards the 'yes' side among voters.
Leinen said "we can only hope with these guarantees, Ireland will follow its 26 partners and will not block the entire integration process, thus isolating the country from the rest of the EU".
