Warren, Biden, Sanders, Buttigieg on Jan. 14, 2020 in Des Moines, Iowa. Photo: Spencer Platt/Getty Images

Six 2020 candidates offered their positions on issues including beating Trump, climate change, impeachment in the seventh Democratic debate Tuesday night.

Why it matters: The debate is the last before the Iowa caucus — the first real test of candidates' appeal to voters — on Feb. 3, as the top four Democrats stand statistically neck and neck with caucus-goers.

Beating Trump

Catch up quick: The argument of who stands a real chance against Trump in 2020 stands on whether Democratic voters prefer a moderate or progressive candidate.

  • Warren: "Since Donald Trump was elected, woman candidates have outperformed men candidates in competitive races."
  • Biden: "The real issue is, who can bring the whole party together," he said. "I would argue that, in terms of endorsements ... I am the one that has the broadest coalition of anyone who's running right now, in this race."
  • Sanders said his status as a Democratic socialist would not be a detriment in a run against Trump.
  • Buttigieg said he, a war veteran, was ready to stand next to Trump, who got a draft referral for bone spurs, and to take on Trump on religion, in light of his own faith. The former mayor of South Bend, Ind., emphasized that Christianity does not belong to a political party.
Climate change

Catch up quick: Extreme weather events and dire scientific reports point to a world entering a make-or-break period to confront global warming. House Democrats introduced legislation last week laying out policies to achieve net-zero U.S. greenhouse gas emissions within the next 30 years.

  • Steyer: "I would declare a state of emergency on day one on climate," he said. Steyer also said he was the right messenger on climate change, in response to CNN pointing out that he made part of his fortune from investing in coal, oil and gas.
  • Warren pledged to stop all new drilling and mining on federal lands on her first day in office, if elected.
  • Klobuchar said she sees natural gas as a transition fuel to get to carbon neutral, when asked why she has not called for a total ban on fracking. She supports a carbon tax.
  • Biden touted his 1986 Global Climate Protection Act and said the U.S. should be investing in infrastructure that raises roads.

Catch up quick: The House will vote Wednesday on a resolution to transmit the articles of impeachment against Trump to the Senate.

  • Biden: "It's irrelevant," he said when asked if it will be harder to run against Trump after he's likely acquitted by the Senate.
  • Klobuchar: "No," she said when asked if Trump will be emboldened by acquittal, adding: "We have a duty to perform here." She said her primary issue with the impeachment process was the ability to call witnesses to the Senate trial.
  • Steyer: He touted the 8-1/2 million Americans that signed his petition to remove Trump from office.
  • Warren: "Some things are more important than politics," she said, saying she would be at the Senate impeachment trial in the weeks leading up to Iowa's caucuses because it is her responsibility.
Universal child care

Catch up quick: The candidates used questions about universal child care as an opportunity to pitch their wealth tax plans and ideas to combat income inequality.

  • Buttigieg: "It makes no sense for childcare to cost two-thirds of somebody's income ... this is happening to folks at every level of the income spectrum." He said child care contributes to the gender pay gap.
  • Warren advocated for her wealth tax plan, saying it would ease the cost of raising children. "I've been there. I remember when I was a young mom, I had two little kids, I had my first real university teaching job — but it was childcare that nearly brought me down."
  • Sanders touted for universal childcare and called the current U.S. plan an embarrassment.
  • Biden repeated his plan to give a $8,000 tax credit to every person in need of child care.
  • Klobuchar: "I actually think that some of our colleagues who want free college for all aren't thinking big enough," she said. "Where are our job openings ... we're going to have a shortage of plumbers," she said, advocating for funding grades k-12.
  • Steyer: He said that, as a billionaire, his children should not be entitled to free public college.
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Editor's note: This is a developing story and will be updated.

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