The Liberal Democrats will turn away defecting MPs unless they truly believe in the party's values, according to Christine Jardine.
The MP for Edinburgh West said potential new members who wish to leave their respective parties must be anti-Brexit, and looking for reform of the British political system.
"If they want to come to us it must be, from their point of view, because they want to change the way politics is done in this country," Ms Jardine told talkRADIO's Mike Graham.
"They have to share our ideals."
She continued: "If there are people who want to work with us from inside the Conservative Party or Labour Party we are always prepared to work with other people for the greater good."
In June, former Change UK member Chuka Umunna defected to the Liberal Democrats, despite previously slating the party online.
In a tweet posted in 2013, Mr Umunna wrote: "Vince Cable talks about increasing the minimum wage, but you can't trust a word the Lib Dems say."
However, since joining the party, he claimed the Liberal Democrats were "at the forefront" of "a progressive and internationalist movement" in British politics.
Mr Umunna's decision to defect for the third time in as many months drew criticism from some in the political sphere, with Labour Party chairman Ian Lavery calling for a by-election in Mr Umunna's seat.
He tweeted: "Three parties in as many months....who's next?".