Chesterfield MP Toby Perkins has said he will remain in the Labour Party after seven of his colleagues quit.
This morning, MPs Luciana Berger, Chris Leslie, Angela Smith, Gavin Shuker, Mike Gapes, Ann Coffey and Chuka Umunna announced their decisions to resign from the party in protest at Labour leader Jeremy Corbyn's approach to anti-Semitism and Brexit.
Mr Perkins said: "I have great respect for the seven colleagues who have today left the Labour Party.
"I sympathise with many of their anxieties but remain of the view that only a united Labour Party will defeat the Tories.
"This is a serious moment and should be neither celebrated nor ignored."
Mr Perkins told the Derbyshire Times he would stay in the Labour Party and added: "It'll be for the leadership - including Jeremy Corbyn and Tom Watson - to show they're taking seriously the concerns that there are in the party."
Mr Perkins, a former critic of Mr Corbyn, previously told the the Derbyshire Times he did not believe the Labour leader was anti-Semitic.
Corbyn 'disappointed' at MPs' decisions
Luciana Berger, MP for Liverpool Wavertree, said she had come to the 'sickening realisation' that the Labour Party was 'institutionally anti-Semitic'.
Mike Gapes, MP for Ilford South, said the Labour leadership had failed to take a lead inaddressing the challenge of Brexit.
Mr Corbyn said: "I am disappointed that these MPs have felt unable to continue to work together for the Labour policies that inspired millions at the last election and saw us increase our vote by the largest share since 1945.
"Labour won people over on a programme for the many not the few - redistributing wealth and power, taking vital resources into public ownership, investing in every region and nation, and tackling climate change.
"The Conservative Government is bungling Brexit, while Labour has set out a unifying and credible alternative plan.
"When millions are facing the misery of Universal Credit, rising crime, homelessness and poverty, now more than ever is the time to bring people together to build a better future for us all."
The MPs who have resigned are not launching a new political party - they will sit in Parliament as the Independent Group.