Aubry was the last of the six candidates to announce she would stand in the election to choose the Socialist party's candidate for the 2012 presidential election. She finally entered the race on June 28th.
In Sunday night's interview, watched by a record 13.5 million people, Strauss-Kahn was asked whether he had hoped to stand for the presidency and whether there had been a pact with Aubry, who was recently first secretary of the Socialist party until she stepped aside to run for the nomination.
"Yes, I wanted to be the candidate," he said. Referring to Aubry, he acknowledged "we had, in effect, a pact."
Before rape charges were brought and later dropped against the former IMF director in May, Strauss-Kahn was the clear favourite in opinion polls to win the Socialist nomination.
Since announcing she is to run, Aubry, who is also the mayor of the northern town of Lille, is currently second placed in opinion polls, behind the front-runner François Hollande.
Hollande's supporters were quick to exploit Strauss-Kahn's mention of the pact on Monday.
"If Martine Aubry is a candidate today, it's because DSK isn't," said Socialist member of parliament André Vallini. "François Hollande, who has never been in any pact or any arrangement, is not a candidate by default or substitution."
On the right, Bernard Debré, an MP with the governing UMP party, also called Aubry the "default candidate" in an interview on BFMTV-RMC.
Aubry's own campaign team hit back at the accusations.
"Before May 14th, DSK wanted to be a candidate, Martine wanted to be a candidate," François Lamy, one of Aubry's key supporters, told AFP.
"They were going to decide together in June. Each had their own constraints, him at the IMF and she as the head of the party. It doesn't mean she was going to give up her place to him."
Late on Monday, Aubry herself finally reacted to her Strauss-Kahn's comments. Speaking to journalists on a trip to Nice, she asked: "do I look like a substitute candidate?"
"If you define a pact as 'have you worked together?', the answer is yes," she said. "If it's whether a decision had been taken, then it's no. I am not the candidate by default but the candidate we need."
François Hollande will get further encouragement from a poll to be published in news magazine Le Point this week. The poll, by IPSOS, puts him as the most liked politician in France, with a score of 54 percent of positive opinions. This puts him ahead of the next two favourites, former finance minister and current IMF head Christine Lagarde (51 percent) and the Socialist mayor of Paris Bertrand Delanoë (49%).
Voting in the Socialist primaries takes place in two stages. The first vote will be on October 9th. The two leading candidates from that will then face each other in a final vote on October 16th.