MK Zvi Hauser responded to Labor Chairman MK Amir Peretz's suggestion to unite the center-left bloc.
Under the proposal, Blue and White, Labor-Gesher, and Meretz, would unite into a single large list.
"There are last-minute difficulties in the merge between the leftist parties and Amir Peretz decided to involve the Blue and White," Hauser told Reshet Bet.
"There is an existential difference between Blue and White, which is a centrist party, and Labor and the Democratic Union, which are leftist parties. It's not relevant."
On Tuesday, reports said the Blue and White was pressuring Peretz to join together with Meretz to ensure the party passes the electoral threshold. In return, Blue and White promised to support Peretz's candidacy as Israel's next president.
Last month, it was reported that Blue and White is planning to offer Labor-Gesher's number two, MK Orly Levi-Abekasis, a place on its own list.
Levi-Abekasis has warned that a merger with the extreme-left would cause the party to lose seats. At the same time, the Green Party's MK Stav Shaffir has urged a merger between all the smaller parties to the left of the center-left Blue and White.