"Right now I'm president, and I'm for it," Obama said at a midday press conference with Singapore Prime Minister Lee Hsien Loong. "And I think I've got the better argument. I've made this argument before. I'll make it again. We are part of a global economy. We're not reversing that."
The remark seemed a rebuke not only to Donald Trump -- who has lambasted the TPP deal on the campaign trail -- but also Hillary Clinton, who also opposes the plan.
"I've got some very close friends, people I admire a lot, but who I just disagree with them. And that's okay," Obama said. "I respect the arguments that they're making. They're coming from a sincere concern about the position of workers and wages in this country. But I think I've got the better argument."
But Congress has shown little urgency in moving forward with a vote to ratify the deal, leaving in limbo one of Obama's signature foreign policy objectives.
Obama, however, expressed optimism that once the election was over, lawmakers would give the TPP due consideration.
"Hopefully after the election is over and the dust settles there will be more attention to the actual facts behind the deal and it won't just be be a political symbol or a political football," Obama said.
Earlier, Obama acknowledged the concerns over trade.
"Forces of globalization and technology have not always benefited everybody evenly," Obama acknowledged. "There are fears and anxieties that people may be left behind. These anxieties are legitimate. They can't be ignored."
He continued, "It means we have to do everything we can to make sure everybody shares in prosperity."
But he still stressed the benefits that would accrue to the US under the massive deal.
Obama also noted that he and Lee had discussed the contentious maritime claims in the South China Sea, where countries are locked in disputes over small islands and freedom of navigation.
"We reaffirmed our shared commitment to building a regional order where all nations play by the same rules and disputes are resolved peacefully," Obama said.
The White House is honoring Singapore's Prime Minister with the highest form of Washington flattery: a formal state visit capped by a black-tie dinner featuring Maryland blue crab and American Wagyu beef. Midday, the leaders will hold a joint news conference.
The grand welcome -- the first of its kind for a Southeast Asian country under Obama -- is another attempt to advance the historic TPP deal, which has been agreed to by 12 member nations but needs congressional ratification.
Despite the lack of traction on Capitol Hill and regular beatings the topic gets on the campaign trail, Obama plans to reiterate his commitment to seeing the deal through Tuesday.
"He will once again say to the Prime Minister that he's committed to getting TPP done, and doing so before the end of his term," Daniel Kritenbrink, Obama's Asia director, said on Friday.
But it's unclear what assurances Obama can provide to the visiting leader from Singapore, one of the 12 signatories to the agreement. Republican leaders in Congress have said they don't plan to bring TPP up for consideration until after November's general election, if at all. And both Donald Trump, the Republican nominee for president, and Hillary Clinton, the Democrat, rail against the deal.
Delegates at last week's Democratic National Convention in Philadelphia voiced strong anti-TPP sentiment, claiming the deal would destroy American jobs.
But Obama insisted in an interview published Monday that he would succeed in getting approval for the deal.
"I know that the politics around trade can be very difficult -- especially in an election year," Obama told Singapore newspaper The Strait Times. "There are legitimate concerns and anxieties that the forces of globalization are leaving too many people behind -- and we have to take those concerns seriously and address them."
"The answer isn't to turn inward and embrace protectionism," Obama said. "We can't just walk away from trade. In a global economy where our economies and supply chains are deeply integrated, it's not even possible."
During talks Tuesday morning, Obama and Lee are also expected to discuss efforts to combat terror, including in Southeast Asia, where Islamist cells are known to operate.