Former Vice President and 2020 Democratic front-runner Joe Biden plans to return to Iowa next Tuesday. He may bump into President Donald Trump who also plans a visit to the state that day.

Biden's campaign was mum on the details of his trip, which marks only his second visit to the key caucus state since formally declaring a 2020 run for the White House on April 25. It's the veteran politician's third try to win the highest office in the land.

Trump is scheduled to attend a GOP fundraiser in West Des Moines and visit an ethanol plant in Council Bluffs during his visit next week. The president is expected to tout his administration's new E15 gasoline rule for ethanol, a policy change seen as a win for farmers since it will allow year-round use of the corn-based fuel.

Farmers gave Trump strong support in the 2016 presidential election, but the administration's trade war against China has resulted in punitive tariffs targeting many of farm state's top agricultural commodities, including soybeans and pork. The president has sought to soften the blow through a new $16 billion farm aid bailout.

Trump's threat to impose 5% tariffs on Mexican goods starting June 10 raises the possibility of additional trade retaliation and fallout for American farmers. The White House said last week it will gradually increase that tariff amount, hitting a maximum of 25% by Oct. 1, until Mexico "substantially stops the illegal inflow of aliens coming through its territory."

While campaigning for the 2018 midterms, Biden talked about the trade war's impact on farmers when stumping for Democratic candidates, including in North Dakota for then-Sen. Heidi Heitkamp, who lost her seat to Republican Kevin Cramer. He also brought up the trade issue during a visit to New Hampshire in mid-May.

"The fact of the matter is that what we're really doing, you can't get much done on trade relative to China by engaging in a trade war that only hurts working people and farmers," Biden said last month. "What you have to do is you need the whole world and the folks who agree with us who are getting beat up by China working together, but he's alienated most of our allies."

A White House official said via email that the president's visit to Iowa and the nation's heartland is "to reaffirm his commitment to supporting and defending America's farmers." The official added that support includes the trade and disaster aid for farmers.

On Tuesday, Biden also may provide more details on his new $1.7 trillion plan to fight climate change, which includes investments in advanced biofuels and "climate-friendly farming" like conservation programs.

Several of Biden's Democratic challengers, including Sens. Bernie Sanders of Vermont, Elizabeth Warren of Massachusetts and Amy Klobuchar of Minnesota, have been outspoken about the plight of family farmers. The Senators have also expressed support for breaking up big agriculture.

National polls show Biden ahead of the pack for the 2020 Democratic presidential nomination, with a double-digit lead against his nearest rival, Sanders. The nonpartisan Real Clear Politics website says Biden's average in polls from mid-May through June 4 was 33.5% to Sanders' 16.7%.

In Iowa, Biden only has a 4-point lead over Sanders, according to the Real Clear Politics average in polls from March 21 to mid-April.

Nationally, Biden has an 8.1-point lead over Trump, the website's poll average from mid-March to mid-May shows. Prior to entering the race, Iowa polling data had Biden running ahead of Trump with up to a 6-point lead, according to the site.

The last time Biden visited Iowa was for a two-day visit April 30-May 1, traveling to three eastern cities for four events. During a stop in Iowa City, he talked about working-class values, health care, education and promised to "restore the soul of America."

"It's good that he is coming back," said Iowa State Rep. Lisa Heddens, a Democrat and longtime Biden supporter who introduced him during his last visit to Des Moines. "But I don't think he needs to go to the level that some of the other candidates do, because he is so well recognized."

Biden plans to skip a high-profile event ahead of the summer caucus season — Sunday's Iowa Democratic Party Hall of Fame celebration in Cedar Rapids. At least 19 presidential candidates are scheduled to speak at the event, making it the greatest single gathering of 2020 Democratic hopefuls to date.

Similarly, Biden skipped the California Democratic Party Convention last weekend in San Francisco. There were 14 Democratic presidential candidates at the convention, and some took jabs at the former vice president who served from 2009 to 2017.

"We cannot go back to the old ways," Sanders said. "We have got to go forward with a new, progressive agenda."

Sanders, meantime, is scheduled to arrive in Iowa on Friday and stay over the weekend for at least seven events, including the Democratic Hall of Fame celebration. This will mark Sanders' fourth trip to Iowa as a 2020 contender, according to his campaign.

Biden appears to be trying to stay above the fray in the crowded field of more than 20 Democrats, focusing on his climate and economic policies rather than taking on party rivals.

"I think the worst thing we could do is get into a match where we're going after each other in the Democratic Party," Biden told the New Hampshire's Concord Monitor in an interview Tuesday. "So I'm going to try my best not to be negative relative to my opponents."