If you want to know how much interest there is in the race for Rep. Kevin Yoder's congressional seat, you got a pretty good idea at a candidate forum Sunday afternoon.

Some 500 people packed the sanctuary at Congregation Beth Torah in Overland Park to hear the five Democrats and one Libertarian running for Yoder's seat.

Yoder, a Republican, was invited but didn't attend. His campaign spokesman, C.J. Grover, said the forum was hosted by "progressive activists" and that Yoder looks forward to debating the issues this fall with the winner of the Democratic primary.

Clearly, Democrats think Yoder is vulnerable in the district that encompasses Wyandotte and Johnson counties, including Overland Park, Lenexa, Shawnee, Spring Hill, DeSoto and Olathe.

Just last week, a fifth Democrat got into race: Mike McCamon lives in Overland Park and has a technology background. He joined the race with labor attorney Brent Welder, investor Jay Sidie (who ran against Yoder two years ago), educator Tom Niermann, tech executive Chris Haulmark and Chris Clemmons, the Libertarian who is also an educator.

Many in the audience were wearing "Defeat Yoder" stickers, but there appeared to be an equal number of those uncommitted to his possible opponents.

“I think I lean towards several of them above the others, but overall I was impressed with the quality of what they said,” said George Halper from Overland Park.

“I took a lot of notes. I’m going to really get involved in getting to know better all the candidates,” Janet Powell said, although she said she was leaning toward Welder and Niermann.

There isn't much daylight on the issues between any of the six men (and they're all men at this point) on the stage Sunday. But in a series of lightening round questions from moderator Nick Haines of KCPT, the audience did see some differences.

The biggest threat to the United States (in the order they answered the question):

Niermann—The environment and climate change.

Welder—Getting rid of President Trump.

Haulmark—Democracy and diversity.

McCamon—More caring for our neighbors.

Sidie—Too much corporate money in politics.

Clemmons—Erosion of Fourth Amendment and other constitutional rights.

What to do about healthcare:

Haulmark—Medicare for all.

McCamon—Disconnect health care from employment.

Clemmons—Do away with 20-year patents on pharmaceuticals which could lower drug prices.

Welder—Medicare for all.

Niermann—Allow Medicare to negotiate drug prices and restore Obamacare individual mandate.

Sidie—Have a public health insurance option.

Guns:

Niermann—Allow Centers for Disease Control to study issue.

Welder—Reimpose assault weapons ban.

Sidie—Expose how much money the NRA gives to those in Congress.

Haulmark—More complete background checks.

Clemmons—Figure out why "society is sick." He says people will figure out a way to kill.

McCamon—Find a better way to keep guns away from criminals.

Sam Zeff is KCUR's Metro Reporter. Follow him on Twitter @SamZeff.