WASHINGTON (Reuters) - U.S. presidential candidate Bernie Sanders, under fire for his democratic socialist views, defended his philosophy on Wednesday as a natural extension of former President Franklin Roosevelt’s New Deal and accused his Republican critics of “corporate socialism.”

Sanders said his vision of democratic socialism would guarantee a fair deal and basic economic rights for all Americans and would be instrumental in beating Republican President Donald Trump in the 2020 election.

Roosevelt’s Depression-era New Deal policies, which included public works jobs, strong banking and financial regulations and the Social Security retirement program, made huge progress in protecting the needs of working families, Sanders said.

“Today in the second decade of the 21st century we must take up the unfinished business of the New Deal and carry it to completion,” he said in a speech at George Washington University designed to fight back against critics including Trump who have attacked him as an extremist for embracing the socialist tag.

Sanders, who is running second in opinion polls among the more than 20 candidates seeking the Democratic nomination for the right to challenge Trump in 2020, said Republicans were more than happy to exercise their own version of socialism by bailing out Wall Street and corporate interests that helped line their own pockets.

“They may hate democratic socialism because it benefits working people, but they absolutely love corporate socialism that enriches Trump and other billionaires,” he said.

Sanders also has taken heat over the socialist tag from some of his Democratic rivals. Before the speech on Wednesday, Democratic candidate John Delaney issued a statement criticizing his views.

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“Socialism -- or any new name Senator Sanders has for it -- is the wrong answer; the right answer is to make capitalism more just and inclusive,” said Delaney, a former member of Congress.

‘MASSIVE ATTACKS’

Other Democratic contenders have adopted many of Sanders’ most notable proposals from his losing 2016 campaign, including his calls for a Medicare-for-All healthcare plan, but have been slower to associate themselves with the socialist label.

Democratic presidential contender Elizabeth Warren, normally aligned with Sanders leading the party’s progressive wing, has said she favors “capitalism with serious rules.”

Former Colorado Governor John Hickenlooper planned a speech in Washington on Thursday that in part will rebut Sanders. In excerpts released by his campaign, he criticized his fellow Democrats for being hesitant to oppose Sanders’ philosophy and said it could help get Trump re-elected.

“Democrats must say loudly and clearly that we are not socialists. If we do not, we will end up reelecting the worst president in our country’s history,” he said in the excerpts.

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Sanders has acknowledged the term socialism makes some voters nervous with its Cold War-era images of government-controlled economies, but said the values of economic justice were a political winner.

“I do understand that I and other progressives will face massive attacks from those who attempt to use the word “socialism” as a slur,” he said. “But I should also tell you that I have faced and overcome these attacks for decades -- and I am not the only one.”

Sanders, a senator from Vermont, endorsed Roosevelt’s 1944 call for a second Bill of Rights that would guarantee economic security.

“We must take the next step forward and guarantee every man, woman and child in our country basic economic rights,” he said, including quality healthcare, education, a decent job, affordable housing, a secure retirement and a clean environment.

“This is what I mean by democratic socialism,” he said.

It was the second time Sanders had given a speech to help explain his democratic socialist views. He offered a similar defense in November 2015 during his ultimately unsuccessful run against Hillary Clinton for the Democratic presidential nomination.