Teamsters President James Hoffa backtracked Tuesday afternoon after suggesting on an earlier conference call with reporters that Barack Obama was not being up front about the conversations one of his economic advisers had with Canadian officials regarding NAFTA.

In questioning the circumstances surrounding that meeting, Hoffa -- whose Teamsters union endorsed Obama in February -- brought up a touchy month-old story first reported by the Canadian television network CTV. The station reported that Obama adviser Austan Goolsbee assured Canadian officials that the Illinois senator's tough talk on the North American Free Trade Agreement -- particularly before the Ohio and Texas primaries on March 4 -- was just political posturing.

The Hillary Clinton campaign used Hoffa's apparently unanswered questions about the matter Tuesday to shift focus and criticism back to Obama, after Clinton top strategist Mark Penn left his campaign post over a meeting he held with Colombian officials on behalf of his public relations firm to advocate a trade deal that Clinton staunchly opposes.

"Senator Clinton's position on the Colombian deal is clear. She is opposed to it," Clinton spokesman Howard Wolfson said Tuesday. "The ambiguity occurs in the campaign of Senator Obama when you have a distinguished surrogate like President Hoffa calling on the Obama campaign to clarify what Mr. Goolsbee said to the Canadians."

But Hoffa later issued a statement saying his confusion is all cleared up.

"To clear up any misunderstanding about my statements, the Obama campaign and Austan Goolsbee have already clarified Professor Goolsbee's meeting with representatives from the Canadian government, and as confirmed by the Canadian government, Sen. Obama's position on NAFTA has not changed," he said. "As I said on a conference call with reporters earlier today, Sen. Clinton has a credibility problem with the working men and women across this country on the issue of trade. This problem is only underscored by Mark Penn's continued role in her campaign."

Hoffa first said on the earlier conference call that Obama should "make a complete -- you know, end this mystery about what happened and I think he should come out and say it ... he should certainly clarify whatever happened in that meeting."

Steve Hildebrand, deputy Obama campaign manager, said he didn't think Hoffa was initially aware that the campaign had "clarified" what happened.

He said Goolsbee had one meeting with the Canadian government and, unlike Penn, was not working for a foreign government. Penn's firm, Burson-Marsteller, had a contract with the Colombian government but lost it after Penn, amid pressure from the Clinton campaign, publicly apologized for the meeting. That offended Colombian officials who canceled the deal.

Both Canadian and Obama campaign officials disputed the account offered by CTV that Obama's adviser was trying to draw a distinction between his public and private views on NAFTA.

FOX News' Aaron Bruns and Bonney Kapp contributed to this report.