Dem 2020 nominee must focus on issue other than Trump, says political scientist

Political scientist Michael Cornfield said on Wednesday that the Democratic nominee in 2020 will ultimately need to focus on an issue other than President TrumpDonald John TrumpSunday shows preview: Shutdown negotiations continue after White House immigration proposal Rove warns Senate GOP: Don't put only focus on base Ann Coulter blasts Trump shutdown compromise: ‘We voted for Trump and got Jeb!’ MORE on the campaign trail. 

"The presidential campaign trail is littered with the carcasses of people who tried to defeat Donald Trump by running against him, instead of for something, on their own issue," Cornfield, the director of the GW Politics Poll, told Hill.TV's Joe Concha on "What America's Thinking."

"Whoever wins the Democratic nomination will be the one who articulates a vision, and has an appealing personality, but above all, has warned that American people that, 'hey, we're ignoring this. We need to take care of this,'" he continued. 

Cornfield's comments come hours after Republicans maintained control of the Senate, but lost their majority in the House in the midterm elections. 

The elections were widely interpreted as a referendum on President Trump's first two years in office. 

Trump on Wednesday appeared to be happy that Republican House incumbents who distanced themselves from him, such as Reps. Carlos Curbelo (Fla.), Barbara Comstock (Va.) and Mia Love (Utah), were all defeated.

The conclusion of the midterms has led to further speculation on who will challenge Trump in 2020. 

Potential challengers include former Democratic Vice President Biden, as well as Sens. Elizabeth WarrenElizabeth Ann Warren2020 Democrats barnstorm the country for MLK weekend Kamala Harris picks Baltimore as headquarters for potential 2020 campaign: report Dem voters split on importance of women atop the ticket in 2020 MORE (D-Mass.) and Bernie SandersBernard (Bernie) Sanders2020 Democrats barnstorm the country for MLK weekend Bill Maher defends Bernie Sanders campaign over sexual harassment allegations Americans need an economy that supports more than the 1 percent MORE (I-Vt.). 

— Julia Manchester