The British prime minister is likely to be pilloried by the domestic media and his political rivals and accused of performing a U-turn.
He told the Financial Times, however, that a limited new treaty, focused on updating the EU’s rules and institutions, did not require a referendum.
It is understood that Mr Blair has discussed the strategy at length with Gordon Brown, the chancellor, who is expected to succeed him as prime minister at the end of June, after the EU summit on June 21 and 22.
Mr Blair expects to agree “the basic outline agreement for a treaty” at the summit – his final act on the European stage – leaving Mr Brown to oversee negotiations on the fine details in the autumn and the subsequent parliamentary ratification.
Rejecting suggestions that Mr Brown could unpick the deal, Mr Blair said: “When we come to the June council we will come with the position of the government.”
He said his chancellor was wrongly depicted in Brussels and some capitals as hostile to the EU. “I think he is pro-Europe and pro-reform and he wants change in Europe – quite rightly,” he said.
Mr Blair thinks it would suit his successor if he took the flak for agreeing to a revamped EU constitution – and ditching the referendum idea – leaving Mr Brown to focus on other issues.
“For us, we are going to get attacked whatever we do, but Europe needs to do it to move forward,” he said in an interview with seven European newspapers in Downing Street. “These issues aren’t going to go away. It’s better to resolve them sooner rather than later.”
Mr Blair spoke of the “big reality” that Europe had to face after French and Dutch voters rejected the EU constitution in 2005, and the need for a new treaty to make an enlarged union of 27 work more effectively.
That would probably include new voting rules, a new EU president and foreign minister, enhanced powers for national parliaments and a slimmed-down European Commission.
Mr Blair said such a treaty would simply amend the EU’s existing legal base, and would not have the characteristics of the constitution, which aimed to re-establish the EU and contained trappings of statehood, such as a flag and anthem.
Asked whether the treaty he had in mind would require a referendum, he said: “No. If it’s not a constitutional treaty, so that it alters the basic relationship between Europe and the member states, then there isn’t the same case for a referendum.”
Mr Blair’s belief that the EU’s June summit in Brussels can end five years of wrangling over the constitution matches the ambition of Angela Merkel, the German chancellor and holder of the rotating EU presidency.
Mr Blair will travel to Berlin next week to discuss tactics with Ms Merkel, who is working to persuade other sceptics, such as Poland and the Czech Republic, of the need for a new text.
The German leader is privately hoping that Nicolas Sarkozy will win the forthcoming French presidential elections, as he also favours a streamlined treaty that he could ratify through the national assembly.