Angela Eagle has faced attack since launching leadership challenge to unseat Labour leader Jeremy Corbyn.
The human rights activist had posted a racist list of MPs who backed the war.
Minutes prior to the launch, the party's general election chief called for government to announce snap poll.
Embattled far-left leader Jeremy Corbyn will contest the challenge while the Conservatives are poised to choose between Theresa May, Andrea Leadsom.
The energy minister is an outsider with the odds ranged against her. But in modern British politics, are all bets off?
Blair's shadow may hang over the party but challengers to Corbyn should still look to his example to win.
But the Labour leader slammed the "governing class" that led the country to war in Iraq.
Mandelson said Corbyn's referendum campaign was 'near sabotage of what the Labour Party believes in.'
The EU referendum has split society—but we should remember racist thugs are the minority.
If the Labour party does not act, it risks losing disillusioned voters to the far right.
Resignations show that a broad sweep of Labour MPs don't believe Jeremy Corbyn has the qualities to lead.
Labour leader denies claims that he defied his party's Remain position.
Leader Jeremy Corbyn is facing an exodus from his top team.
Investor anxiety continues with more share price falls following Britain's vote to leave the EU.