MANILA - Former president Joseph Estrada on Thursday said he is open to a coalition with senator and presidential candidate Francis Escudero but rejected a proposal to take the latter as his running mate in the 2010 elections.

In an interview, Estrada admitted that he invited the senator to become the United Opposition's vice-presidential candidate, an offer that was rejected by Escudero. The former president later chose Makati Mayor Jejomar Binay to be his running mate.

Estrada said Escudero's decision to leave the Nationalist People's Coalition after 11 years will have an impact on the latter's decision to run for higher office. He said that while Escudero is a smart and capable politician, he also noted that no independent candidate has won in past presidential elections.

"In the history of presidential elections, wala pa akong nakitang presidenteng nanalo na walang partido. There is a saying na politics is addition. You have to have a party kaya minsan may coalition, kasi hindi pwedeng nag-iisa ka lang," he said.

He declined to comment on Escudero's reasons for leaving the party.

Estrada said he remains confident of winning the 2010 presidential election, albeit with a possible lower margin over his opponents. The former president said the political landscape has changed since he was elected president in 1998 with 11 million votes.

He added, however, that his experience gives him an edge over the other candidates.

Asked if he was worried that there were already too many candidates for president in the coming presidential elections, the former president said that this could only ensure that a member of the opposition would emerge president in 2010. He pointed out that opposition candidates such as himself, Sen. Benigno "Noynoy" Aquino III and Sen. Manny Villar regularly top opinion polls on who should replace President Arroyo.

He also said Defense Secretary Gilbert Teodoro is not the only pro-administration candidate running in the presidential election next year.

"While there will be more than one opposition member who will run for president, neither is the administration united, what with (Public Works Secretary Hermogenes) Ebdane and (MMDA Chair Bayani) Fernando also running. With opposition candidates in the top slots in the past surveys, we are least sure that the president in 2010 will come from the opposition," he said.