ABC News’ Matthew Jaffe Reports: Former Democratic vice-presidential candidate Sen. Joe Lieberman, ID-Conn., cautioned Sunday that a decision has not been made on whether he will speak at the Republican national convention in support of Sen. John McCain, R-Ariz., but strongly insinuated that he will in fact do so. Lieberman, now an independent senator who caucuses with the Democrats, has been a vocal supporter of McCain for president and he may speak on his behalf at the Republican convention in Minneapolis later this summer. "That decision hasn’t been made," Lieberman said on NBC’s "Meet the Press". "If John McCain feels that I can help his candidacy, which I think it’s so important to elect him our next president, I will do it." Lieberman’s comments echo what he has said recently about the convention, but the senator then strongly implied that he will appear at the GOP gathering. "I’m not going to go to that convention, the Republican convention, and spend my time attacking Barack Obama. I’m going to go there really talking about why I support John McCain and why I hope a lot of other independents and Democrats will do that and frankly, I’m going to go to a partisan convention and tell them, if I go, why it’s so important that we start to act like Americans and not as partisan mud-slingers." "Sounds like you’re going to go," replied host Tom Brokaw. "Sounds like that to me too," agreed Sen. John Kerry, D-Mass., as all three men laughed. There is speculation that Lieberman might even appear at the convention as McCain’s vice-presidential nominee, but Lieberman has said he is not interested in the position, adding that McCain could find someone better. Lieberman was Al Gore’s vice-presidential running mate on the Democrats’ unsuccessful 2000 ticket. "Been there, done that," the Connecticut senator has said in the past when asked about the possibility of holding that position with McCain. "It’s not happening," Lieberman spokesman Marshall Wittmann told ABC News this week. Republican party rules would also seem to make it difficult for Lieberman to share the ticket with McCain. And as ABC News’ Jan Crawford Greenburg and Howard Rosenberg reported last month, Lieberman’s appearance could loose him both his Senate committee and his ability to caucus with Democrats.