The buzz grew louder this week when McGuinty's own brother, Ottawa MP David McGuinty, said the premier would be a good choice for the party, given his track record of three straight election wins.
But the premier assured provincial party members on Saturday that he's not seeking the federal leadership — his third denial in as many days.
"People see our success and they're asking me about leading the federal party," he said in a speech in Niagara Falls, Ont., where provincial Liberals gathered for their first major post-election meeting.
"So I want you to know: I love my country, but I am committed to my province and my party."
As for his younger brother, the premier threatened to relegate troublemaker David to social Siberia at the next gathering of the McGuinty clan.
"He's going to have to sit at the little card table for Christmas dinner," McGuinty joked to reporters. "He's not going to sit at the dining room table with the rest of us."
David's comments weren't helpful for the premier, who's been trying to quash leadership speculation that's been swirling since the Oct. 6 provincial election.
McGuinty managed to win a historic third term — the first time a Liberal has pulled off such a feat in more than a century — but his party was reduced to 53 seats, just one short of a majority.
The premier has repeatedly denied that he'll seek the federal leadership, even taking to Twitter to make sure the message got out.
The rumours have been an irritant for McGuinty, who is trying to assure his party and Ontario voters that he has the right plan to get them out of massive deficits, job losses and a fragile economy.
His party is trying to push through two of its campaign promises in a new minority legislature: a home renovation tax credit that would keep seniors in their homes longer and a tuition cut for full-time post-secondary students.
McGuinty said he believes the tax credit bill, introduced this week, will gain enough support in the House to become law.
The Progressive Conservatives have already indicated that they won't support the legislation, but the NDP hasn't made any commitments yet.
However, it's unclear what kind of incentive McGuinty would be willing to offer the NDP after slapping down a private member's bill to cut the HST on home heating.
Although the HST bill passed second reading with the support of the Tories, the governing Liberals have said they'll block the bill from becoming law by refusing to call it up for third and final reading.
It shows that McGuinty has learned nothing from the fall election, which saw a majority of Ontarians cast ballots for non-Liberals, said Tory critic Monte McNaughton.
The premier says he's open to new ideas now that Ontario's new political landscape has changed, but it's just talk, McNaughton said. As a rookie MPP, he said he was surprised that the government could quash legislation that received most of the votes.
"I thought when two parties join together and put a bill forward, a good idea ... that's the majority," he said. "So I thought that McGuinty would listen and respect (it), but again, he's following through with his own agenda and ignoring the will of the legislature on that issue."