CNN polled Democrats on their 16 favorite 2020 presidential candidates, and while Sen. Sherrod Brown, D-Ohio, did not appear, the final list could be much longer.

DALLAS —

If you thought having 17 Republican presidential candidates in 2016 was excessive, wait until you see the even longer list of 2020 Democratic presidential hopefuls. You won’t have to wait long!

Ohio Sen. Sherrod Brown, who just won re-election to a third term in the Senate, recently responded to a question from the Cincinnati Enquirer about a presidential bid, “I’d be lying if I said I wasn’t considering it.” Yes, he would be.

There’s an old quip that every senator thinks he or she is eminently qualified — and perhaps deserves — to sit in the Oval Office. Voters, on the other hand, often have a different idea.

Despite numerous sitting U.S. senators having tried, they almost never win a presidential race — or even their party’s nomination.

Barack Obama was the last sitting senator to win a presidential election. Prior to him you have to go all the way back to ... John F. Kennedy in 1960.

Brown faces another major hurdle: No one’s clambering for him to run.

CNN polled Democrats in October asking who was their favorite 2020 presidential candidate. Former Vice President Joe Biden placed first and Sen. Bernie Sanders second. Brown didn’t even make CNN’s list of 16 possible contenders.

Of course, the final list could be much longer. The University of Virginia’s Dr. Larry Sabato, one of the country’s most respected election forecasters, has identified some 34 Democrats, including Brown, who have been mentioned or are considering a presidential bid.

That’s twice the number of Republicans who ran in 2016.

Sabato’s list includes celebrities such as Oprah Winfrey, Mark Cuban and Dwayne “The Rock” Johnson.

It also includes a number of current senators, including California’s Kamala Harris, Massachusetts’ Elizabeth Warren and New Jersey’s Corey Booker, along with some members of the House of Representatives and a sprinkling of current and former governors.

And then there are some, let’s say, unconventional options, such as attorney Michael Avenatti, who was recently arrested on a domestic violence charge and whose law practice was evicted from its offices for not paying the rent.

Oh, and Democrats Mark Penn, a pollster and former adviser to Bill and Hillary Clinton, and Andrew Stein recently wrote in The Wall Street Journal, “Hillary will run again.”

Recognizing the leftward shift of the Democratic Party, they proclaim she’s “reinventing herself as a liberal firebrand.” She’ll need to.

Bernie Sanders has ignited a neo-socialist movement in the Democratic Party, made up of energized young people like newly elected Rep. Alexandria Ocasio-Cortez.

The 2020 quest for the Democratic nomination will be all about who’s lefter-than-thou.

Virtually every Democratic contender will be calling for a single-payer, government-run health-care system, universal basic income, free college tuition, higher taxes on companies and the wealthy, massive green energy spending and a ramp-up of regulations on business.

While Brown can claim to be a long-standing member of the Democratic Party’s progressive wing — coming in 10th place in GovTrack’s 2017 ranking of the most liberal senators — he may not be as radical as the party’s movers and shakers. Perhaps more importantly, he just seems like yesterday’s news.

The Republican leadership struggled in the last presidential election with how to deal fairly with so many candidates.

Democrats may face a similar dilemma.

Those who don’t poll well after only a short period of time should voluntarily drop out so that a small number of viable candidates can more effectively share the limited amount of media attention and campaign contributions.

If Brown is not a viable candidate, it will become obvious to most people fairly quickly. The bigger challenge will be getting Democratic candidates who are trailing far behind to accept what the voters already know.

Merrill Matthews is a resident scholar with the Institute for Policy Innovation. He holds a Ph.D. in the humanities from the University of Texas.