Former Labour MP Mr Galloway is taking the fight to Mr Watson in the next general election, by announcing he plans to stand against him in West Bromwich East as an independent candidate.
He has raised nearly £12,000 to fund his campaign, and now Mr Watson has responded by setting up a gofundme page of his own.
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In a statement he said: "George Galloway has announced that he’s intending to stand against me in West Bromwich East at the next general election.
"Where Labour stands for solidarity, equality and hope, Galloway has sown division, hatred and distrust.
"Mr Galloway seeks to silence me, but I won’t be cowed.
"Help fund my campaign and say no to the politics of hate."
Mr Watson's campaign raised more than £2,000 of its £25,000 goal in its first three days of going live.
Mr Galloway, who was expelled from Labour in 2003, announced his campaign by accusing Mr Watson of attempting to block Brexit and trying to "wreck" Jeremy Corbyn's campaign for Number 10.
He pledged to back a Labour government under Mr Corbyn if elected.
Meanwhile allies of Mr Watson have rallied around the deputy leader. They include Dudley North MP Ian Austin, who quit Labour over anti-Semitism and bullying.
He said “As a local MP, Tom Watson has spent almost 20 years standing up for people in the Black Country, as a defence minister, he stood up for our armed forces and as Labour’s deputy leader, he stands up for proper decent, mainstream Labour values and opposes extremism and racism every day of the week.
“Tom loves this country and he stands up for the values that make our country great: decency, fairness, tolerance and equality.
“That’s why the hard left are coming after him.
“We support our armed forces, and we stand up to dictators, instead of fawning in front of them like George Galloway did when he praised Saddam Hussain.”