Washington (CNN) The possible entrance of former Starbucks CEO Howard Schultz into the 2020 race as an independent candidate has made Democrats and some never-Trump Republicans really, really, really, really, nervous.

The negative reaction has been swift and striking and somewhat surprising. (See former Obama staffer Bill Burton's Twitter feed.)

The fear is that Schultz, with his $3 billion, can spend endlessly on a bid, get on ballots in every state, command attention on TV and dilute the anti-Trump fervor felt by about 60% of the country

"He should stick to coffee," Democratic Rep. Pramila Jayapal, who represents most of Seattle, quipped to reporters -- including CNN's Ashley Killough -- on Tuesday.

"If he wants to run, he should run as a Democrat," added the Congressional Progressive Caucus co-chair. "I don't understand why he's running as an independent."

Democratic Rep. Marc Pocan, the other caucus co-chair, said Schultz is "carving out the grumpy-get-off-my-lawn lane."

"He seems to be criticizing everything," Pocan said. "He wants to find his own lane to run in, but he doesn't seem, for a billionaire, to be especially astute to how politics is."

Where are the votes?

JUST WATCHED Schultz heckled at book event: 'Don't help elect Trump!' Replay More Videos ... MUST WATCH Schultz heckled at book event: 'Don't help elect Trump!' 01:36

And for now, nobody (except maybe Schultz) actually thinks he can win the White House, given how strong the two-party system is

Who is the Schultz voter? Is it the kind of voter who backed Green Party candidate Jill Stein in 2016, possibly taking votes away from Hillary Clinton? Or is it the kind of voter who backed Libertarian Party candidate Gary Johnson in 2016, possibly taking votes away from Hillary Clinton? Or did Johnson take votes away from Trump?

President Donald Trump clearly buys the argument that Schultz, a life-long Democrat, would take votes away from the Democrat. On Twitter he said Schultz didn't have the guts to enter the race -- i.e. please, please, please get into the race and help me in 2020.

So far, Schultz's testing of the political waters hasn't been so great.

"Don't help elect Trump, you egotistical billionaire a**hole," a protester yelled at a Schultz book event in New York City Monday night. "Go back to getting ratio-ed on Twitter. Go back to Davos with the other billionaire elites who think they know how to run the world. That's not what democracy is."

This heckler suggests a few dynamics at play that will shape Schultz's political fortunes.

People either really love or really hate Trump. It's not that the middle is silent, it's just not really there.

While the share of people who call themselves independents is at an all-time high, the partisanship among those independents is also at an all-time high. Independents lean toward one party or the other, and while they have some negative feelings toward the party they lean toward, they really hate the opposing party, according to one Pew poll

Speaking of hate ... the class of people who isn't exactly beloved? Billionaires! Yes, Trump is a billionaire, but he ran as a cultural conservative, "blue-collar" billionaire, who guaranteed no cuts to Medicare or Social Security. He ran as the "King of Debt" ... as a Republican.

Schultz is betting that there is a block of voters who are up for grabs and alienated from the party they identify with -- concerned about the cost of government programs and debt and deficits -- and that they see a centrist billionaire coffee guy as just the person to fix it

Those don't sound like Stein, Johnson or Ralph Nader-type voters. They actually sound more like Republican voters, who, at least according to polls , are still very high on Trump and in theory care about curbing government spending.

What are the policies?

But Schultz isn't at all deterred. (Are rich businesspeople ever deterred from the idea that their skills are transferable?)

On ABC's "The View," Schultz, directly criticized Democratic Sen. Kamala Harris, and by extension, all the Medicare-for-all Democrats, saying that he didn't agree with that "kind of extreme policy." (No word yet on what policy he does agree with.)

"If he runs against a far, left progressive person who is suggesting 60-70% tax increases on the rich and a health care system we can't pay for, President Trump is going to get re-elected," Schultz said, raising a tax idea suggested by Rep. Alexandria Ocasio-Cortez, D-New York, who is not old enough to run for President.

A recent Fox News poll shows broad support for increasing taxes on families earning over $1 million a year -- 65-70% support increasing tax rate for this group.

Schultz should also look at the recent polling on Medicare-for-all by the Kaiser Family Foundation . A majority of Democrats and independents favor various iterations of this idea. And even a majority of Republicans favor allowing people over age 50 to buy into Medicare. The one caveat on the polling: Not all Medicare expansion plans are the same and there is more support for some than for others, notes CNN's Grace Sparks

American political campaigns are littered with candidates who are media darlings, who gain little traction among voters because their base isn't real, it's just been conjured up by TV talking heads. Wesley Clark, Mitch Daniels, Jon Huntsman and Bill Bradley come to mind.

The two-party ticket is a similar fantasy. In reality, people's party affiliation is very often an expression of their identity -- of what they like and just as importantly what they don't like.

Schultz's neither-here-nor-there approach to the party system and the policies they represent sounds good in theory, but in reality voters are attached to party ideology, leaders and labels -- even if they don't like to admit it.