Change UK leader Heidi Allen has suggested the party could form a partnership with the Liberal Democrats.
Ms Allen said she would like to form a “collective… with like-minded colleagues”, although not necessarily a single, centrist group.
Change UK’s Chuka Umunna said the two parties could form a general election pact not to stand against each other.
But Ms Allen told the BBC’s Pienaar’s Politics she would go further: “I would like us to be in the same vehicle.”
Change UK – originally known as The Independent Group – was formed at the start of the year by 11 MPs who quit Labour and the Tories, partly due to their policies on Brexit.
In March, the pro-Remain group applied to become a party with the name Change UK and was given approval in April, meaning they could field candidates in the European elections.
When the Lib Dems launched their “Stop Brexit” European parliamentary election campaign in April, leader Sir Vince Cable remarked that it was “a pity” that Change UK had not agreed to running a combined campaign.
“The Liberal Democrats made it very clear we were happy to work with others. It wasn’t reciprocated and we are going our own way,” Sir Vince said.
The Lib Dems went on to enjoy significant gains in May’s local elections.
On Saturday, Change UK’s Mr Umunna told the BBC’s Today programme: “The Remain forces in this country need to work even more closely together than we have managed to achieve up to this point, between now and the general election.”
He went on to say that an electoral pact not to field candidates against each other “would be sensible”.
And Ms Allen told Pienaar’s Politics: “I would go one step further. I would like us to be in the same vehicle.”
Asked if that meant the same party, she replied: “Yeah, probably, I don’t know. This partisan thing completely passes me by and when I look across Europe, they seem to do pretty well with coalitions.
“I don’t know what the format will be, but will we be singing from the same hymn sheet?… Let’s call us a collective, somewhere in the middle with other like-minded colleagues.”
Asked if it meant Change UK joining the Liberal Democrats, she said: “I genuinely feel that to be a real insurgent force, and for all the different reasons but the same potency as [Brexit Party leader] Nigel Farage, we need to be new, we need to be brand new.
“If we are just a bigger version of something that people have heard of before, I just don’t think it’s going to cut it. I think the country needs something very dynamic.”
She predicted a wave of Conservative defections if Boris Johnson wins the Tory leadership contest and said many Labour MPs were disappointed by leader Jeremy Corbyn’s unwillingness to commit to another referendum on Brexit.