Eight 2020 Democratic presidential candidates are seen in a combination from file photos
FILE - Eight 2020 Democratic presidential candidates are seen in a combination from file photos.

WASHINGTON - A dozen Democratic presidential candidates will be on stage for the party’s next primary debate Tuesday on the campus of Otterbein University in Westerville, Ohio.

This will be the fourth Democratic debate since June and will feature the largest group on stage for a single debate.  Hawaii Congresswoman Tulsi Gabbard and Tom Steyer, a former hedge fund investor and environmental activist, will join the ten Democrats who took part in the previous debate in September.

It is likely that the impeachment inquiry targeting President Donald Trump will be a major focus of discussion on Tuesday.

WATCH: Jim Malone's video report

Last week, former vice president Joe Biden joined the other Democratic contenders in calling for the impeachment of Trump during a speech in Rochester, New Hampshire.

FILE - Democratic presidential candidate former Vice President Joe Biden gestures during a campaign stop in Manchester, N.H., Oct. 9, 2019.

“He has already convicted himself in full view of the world and the American people," Biden said. "Donald Trump has violated his oath of office, betrayed this nation and committed impeachable acts.”

House Democrats began the impeachment inquiry after a whistleblower complaint surfaced that focused on a phone call between Trump and Ukrainian President Volodymyr Zelenskiy on July 25.

A summary of the transcript of the call shows Trump urged Zelenskiy to open an investigation into Biden and his son, Hunter, who at one time was on the board of a Ukranian gas company.

Trump says the call was "perfect" and that he did nothing wrong.

Biden v. Warren

Biden has a lot at stake in the upcoming debate because his main rival, Massachusetts Senator Elizabeth Warren, has been gaining on him in the polls.  Recent national polling averages compiled by RealClear Politics show the two running about even in recent weeks, with Vermont Senator Bernie Sanders in third place.

FILE - U.S. Democratic presidential candidate Senator Elizabeth Warren (D-MA) responds to a question during a gun safety forum in Las Vegas, Nevada, Oct. 2, 2019.

Warren told reporters in California last week that she has no hesitation in coming to a judgment on Trump’s actions regarding Ukraine and Biden.

“What he has done is he has committed impeachable offenses and he should be impeached.”

In addition to watching the dynamic of Biden and Warren together onstage, Tuesday’s debate will also be an opportunity for Sanders to show he is up to the rigors of the campaign trail after suffering a heart attack this month.

Sanders recently sent out a campaign video to supporters thanking them for their support during his illness.

FILE - Democratic 2020 U.S. presidential candidate and U.S. Senator Bernie Sanders (I-VT) speaks at a campaign stop in Hooksett, New Hampshire, Sept. 30, 2019.

“And I also want to say that I am feeling great.  I am getting my endurance back and I look forward to getting out on the campaign trail as soon as possible.”

But analysts expect that much of Tuesday’s debate will focus on President Trump.

“I think impeachment is going to be front and center and I think the candidates are going to be all very strong on the fact that they are for impeachment,” said John Fortier of the Bipartisan Policy Center in Washington.  “I don’t think there is going to be much daylight between them.”  Fortier is a guest on this week’s “Encounter” program on VOA.

Also rans

Those Democrats running behind the frontrunners see the Ohio debate as another opportunity to try and break through to the wider Democratic primary electorate.

California Senator Kamala Harris has slipped in the polls in recent months and has refocused her efforts in going after the president.

FILE - Democratic presidential candidate Sen. Kamala Harris, D-Calif., speaks at the Democratic National Committee's summer meeting, Aug. 23, 2019, in San Francisco.

“He is getting Americans to turn on each other, and we need to heal.  And I know I am uniquely able to bring our country together,” Harris told attendees at a recent union event in California.

For others mired even further down the polls like Congresswoman Gabbard, the next debate may represent one of their last chances to have an impact on the race.

“The most well known and the most famous people are at the top of the polls, but there are still a lot of people who are undecided and who are keeping their minds open to other choices,” Gabbard told reporters at a recent candidate's event in South Carolina.

In addition to those already mentioned, the debate will feature New Jersey Senator Cory Booker, South Bend, Indiana, Mayor Pete Buttigieg, former housing secretary Julian Castro, Minnesota Senator Amy Klobuchar, former Texas congressman Beto O’Rourke and tech entrepreneur Andrew Yang.

The debate will be broadcast on CNN.

General election debates

Looking ahead to the general election campaign next year, the Commission on Presidential Debates has announced the debate schedule leading up to the presidential election in November of 2020.

There will be three presidential debates and one between the vice presidential running mates of both major party nominees.

The first presidential debate will be held September 29 at the University of Notre Dame in Indiana.  The second will be held October 15 at the University of Michigan in Ann Arbor and the third will be on October 22 at Belmont University in Nashville, Tennessee.

The sole vice presidential debate will be held on October 7 at the University of Utah in Salt Lake City.

Democrats will continue holding their debates as they move toward the start of primary and caucus contests in individual U.S. states that begin in February.

The party envisions those debate fields getting smaller as the process continues, and the next one, to be held in November, has stricter qualification criteria.

Candidates will have to show higher donor support with 165,000 individual donors, and a better showing in polls with at least 3% support in four national polls or 5% support in polls of people in states that are early on the voting calendar.

The Democratic presidential candidate will be officially named at the party's convention in July 2020.