Robert F. Bukaty, AP Photo / Democratic presidential candidate Sen. Amy Klobuchar, D-Minnesota, speaks at her election night party Tuesday in Concord, New Hampshire.

Here we are facing what feels like the loaded end of a double-barreled gun known as early voting for Super Tuesday's Tennessee primary in a year when the stakes have never been higher for choosing the right Democratic presidential nominee.

As Republican President Donald Trump careens off the rails and plunges our republic closer to an autocracy, Democrats have more than a handful of good candidates, all with good ideas and good hearts. The primary question is how to narrow the choices to exactly the right person to kick Trump out of the Oval Office.

Vermont Sen. Bernie Sanders, an Independent who has billed himself as a Democratic Socialist, is now the front-runner, while the expected front-runner, former Vice President Joe Biden, is losing steam, having come out of the first two contests of the year in Iowa and New Hampshire in fourth and fifth place, respectively.

If history is any guide, Sanders or former South Bend, Indiana, Mayor Pete Buttigieg might be the party's ultimate choice because, since 1972, no candidate from either party has placed below second in both Iowa and New Hampshire and still won the nomination. Buttigieg won Iowa, and Sanders came in second. In New Hampshire, it was the other around. Amy Klobuchar surged to make a strong third-place showing in New Hampshire.

All this has Democrats' blood pressures rising. Stated more clearly, Bernie and Buttigieg have Democrats' blood pressures rising. Sanders, especially, is worrying many. We're no different.

(MORE: Sanders edges Buttigieg in New Hampshire, giving Democrats 2 front-runners)

While Sanders has passion and a penchant for bold ideas, many of which we like, the more he says "revolution," the more we see him as unelectable. And if he's unelectable in November because the vast swath of moderates in America stay away from the polls, well then, Trump will have another four years.

That simply cannot be allowed to happen. To ensure that we can dump Trump and address our increasing serious problems with climate, health care, wage gap, education and infrastructure, we need clear heads, not more bomb throwers.

That may be less elusive than the Sanders victory made it seem. Consider these New Hampshire primary numbers: Sanders won, but he barely edged out the more moderate Buttigieg and, overall, the primary moderates got more votes.

There also is what voters across the country tell Gallup they would support:

* 93% of voters now say that they would be willing to vote for a well-qualified woman, up from 33% in 1937.

* 96% say they could support a black candidate, up from 38% in 1958.

* 78% of voters say they would be willing to support a gay candidate, up from 29% in 1983. (Indeed, Buttigieg, 38, might face more resistance because he is young than because he is gay, as only 70% are willing to back a candidate under 40.)

Yet there is one kind of candidate for whom Americans are far less enthusiastic: Only 45% say that they would be willing to vote for a socialist. Sanders, 78, also faces another hurdle: Only 69% say they would consider a candidate over 70.

By the way, Biden and newcomer Mike Bloomberg are 77; Trump is 73 and Elizabeth Warren is 70.

(MORE: Bloomberg rallies Chattanooga: 'Trump is afraid of me.')

This brings us back to Super Tuesday's early voting — which began in Tennessee on Wednesday and continues through Feb. 25 before the March 3 election date.

We've watched these numbers, watched these candidates, watched their ads and watched their debates.

Here are the takeaways:

* Bloomberg's ads — along with the possibility that he expands Democrats' safety net with another strong candidate — are seductive, but ...

What other skeletons — like the audiotape about search and frisk — lurk in his closet? If his future apologies are as unsatisfying as the one he offered for this, he may not really bring much to the table beyond Wall Street glitter. Meanwhile, he pushes other deep-bench candidates off the cliff.

* Biden may surprise us and still have it in him to overcome the lows of an early campaign, but ...

He has now run for president three times and never won a primary. Or come in second. Or third. It is entirely possible that his best days are behind him.

* Buttigieg, on the other hand, has the heart of Joe Biden and twice the glib reasoning, but ...

He has too little experience, still. Unlike Biden, Buttigieg's best days are ahead of him. Come back in four years, Pete.

(MORE: Democrats seek path through diverse states after Iowa, New Hampshire)

* Warren, like a more good-natured Sanders, doth lecture and bomb-throw too much.

That leaves surging Amy Klobuchar, who has heart, experience and a passion for uniting — and leading — leaders. She's passed plenty of legislation. And, in her words, she has the "grit" of a heartland doer to keep seeking opportunities to help ordinary Americans make a better America.

Her best days increasingly seem to be right here, right now.