WASHINGTON (Reuters) - The 2020 Democratic White House race, until now a cordial affair with no personal attacks and few policy disputes, is starting to get scrappy.

Democratic U.S. presidential candidate and former Vice President Joe Biden addresses a campaign rally in Cedar Rapids, Iowa, U.S., April 30, 2019. REUTERS/Jonathan Ernst

Since former Vice President Joe Biden entered last week as the front-runner to win the Democratic nomination, Senator Bernie Sanders of Vermont has taken a swing at Biden’s support for global trade deals and his 2002 vote to authorize the Iraq war.

Former Congressman Beto O’Rourke of Texas questioned Biden’s backing from big-money outside political groups, and Senator Elizabeth Warren of Massachusetts has noted Biden’s work “on the side of the credit card companies.”

Washington Governor Jay Inslee took aim at a different rival, criticizing O’Rourke’s congressional record on climate change after O’Rourke unveiled a $5 trillion plan to invest in clean energy technology and infrastructure.

With 20 Democrats vying for attention in the battle for the right to challenge Republican President Donald Trump in 2020, some in the party said it was only a matter of time before they began to turn on each other.

And Biden, clearly in the lead in polls, provides an easy target for the herd now that he has formally joined the race.

“It’s just the beginning,” said Jennifer Palmieri, a senior adviser to Democratic nominee Hillary Clinton’s 2016 campaign. “In a big field, there will be some early skirmishes as people position themselves.”

The criticism of Biden, a centrist who spent eight years as President Barack Obama’s No. 2, is an early glimpse of the sort of attacks he is likely to face from his more liberal rivals in a race that will be heavily influenced by the party’s progressive activists.

Sanders, the independent who challenged Clinton from the left during the 2016 Democratic primary, criticized Biden’s past support of the North American Free Trade Agreement (NAFTA) and other trade deals that he says have cost Americans jobs.

“When people take a look at my record versus Vice President Biden’s record -- I helped lead the fight against NAFTA, he voted for NAFTA,” Sanders said on CNN on Monday night, adding that he also helped lead the fight against permanent normal trade relations with China, which Biden supported.

“I strongly opposed the Trans-Pacific Partnership; he supported it. I voted against the war in Iraq; he voted for it,” Sanders said.

“I like Joe Biden; Joe is a friend of mine,” he said. “I think what we need to do with all of the candidates is have an issue-oriented campaign, not personal attacks.”

BIG MONEY

In a fundraising appeal on Tuesday, O’Rourke’s team noted Biden’s support from a super PAC, one of many outside groups that can raise and spend unlimited sums of money but are not affiliated with the campaign.

“We’re trying to campaign the right way — the real way — by traveling across the country and listening to Americans, and by relying on the support of regular, everyday people chipping in what they can afford,” the O’Rourke fundraising appeal said.

Warren said at a campaign event after Biden’s entrance in the race last week that Biden had taken the side of credit card companies in a 2005 vote on a bill that made it harder for some people to file for bankruptcy.

Biden, who spent more than three decades as the U.S. senator from Delaware, has long been criticized by liberals for his ties to the financial industry, which is prominent in the state.

Inslee, who has put his efforts to fight climate change at the forefront of his long-shot campaign for the White House, criticized O’Rourke and his climate change plan.

“Beto O’Rourke will need to answer why he did not lead on climate change in Congress and why he voted on the side of oil companies to open up offshore drilling,” he said in a statement on Monday.

Palmieri said the attacks were flying early in a Democratic race that will not have its first nominating contest until early February 2020 in Iowa, but that was to be expected in a historically crowded field.

While Sanders has always been willing to confront those he disagrees with, she said, some other top contenders might hold off until later in the year on drawing contrasts with their opponents.

“Right now, no one is fighting for their life,” she said. “Those who see themselves as more viable contenders can have some caution about picking a fight too early.”