The US and Brussels-based Transatlantic Business Council (TABC), a cross-sectoral business association representing global companies, says "intensive and sustained" efforts are still being made to make the transatlantic deal a success.
Its CEO Tim Bennett intervened after controversial comments on Sunday by German deputy chancellor and economy minister Sigmar Gabriel.
Gabriel sparked widespread protests when said he believed the possibility of agreeing a trade deal was effectively dead.
He said, "In my opinion, the negotiations [over a free trade deal] with the US have de facto failed, even though nobody is really admitting it."
On Thursday, Bennett responded by urging EU leaders to give their support to TTIP.
While he accepted there were "numerous objections" to the trade deal and "no one is under any false illusions as to how difficult it will be to conclude the talks," Bennett robustly refuted Gabriel's assertion that negotiations on the deal had failed.
However, Gabriel found an unlikely ally in the shape of GUE/NGL group deputy Helmut Scholz who agrees that TTIP "is failing" and should be abandoned.
Scholz, a German MRP, said his group would welcome any decision to scrap the TTIP talks, adding that talks on CETA, a similar trade deal between the EU and Canada, should be consigned to the scrapheap.
"These are two major threats to Europeans," said Scholz.
With CETA edging towards being approved by the European Parliament and national parliaments, the GUE/NGL group - in conjunction with the Greens and the S&D group - has organised a special hearing later this year to discuss the deal.
The debate, 'CETA, TTIP: Two sides of the same coin' is on 6 September and includes Pascal Lamy, former Director-General of the WTO.
Other speakers include Penny Clarke, Deputy General Secretary, from European Public Service Union (EPSU) and Cécile Toubeau, from the NGO Transport and Environment.