The Czech and Polish situations combined with the treaty's recent rejection by Irish voters amount to a major setback for the treaty to take effect by the middle of next year, The Financial Times reported Wednesday.
"It's not impossible to do it by next June but it is touch and go," one senior EU diplomat told the newspaper.
To date, 18 of the EU's 27 national parliaments have approved the treaty's reforms to EU institutions and voting procedures.
However, Czech Republic President Vaclav Klaus has declared the Lisbon treaty dead while in Poland President Lech Kaczynski has held back signing the treaty following its approval by his country's parliament.
When EU leaders meet in Brussels on Thursday they expect to learn from Premier Brian Cowen why Irish voters rejected the document.