Is this a 1972 moment for Democrats?

The most important political tweet recently came on Veterans Day. And no, it wasn’t from whom you think.

It went like this: Grateful to all who have served. More than ever, today you are in our thoughts as we celebrate your sacrifice and service. Let’s spare no expense as a country to ensure that you receive the care and services you’ve earned. The sender? Beto O’Rourke, the Democratic congressman who earlier this month lost a bitter and brutal Texas Senate race to Ted Cruz. And the broad political meaning of this tweet? O’Rourke is still in the game, conducting himself as if he won that contest rather than lost it, offering a comment that was remarkable because it was thoroughly unremarkable, sharing thoughts completely in keeping with expectations at a time when all political expectations are being shattered.

No one knows right now what O’Rourke’s plans and destiny are once his congressional term ends in the first week of January. But he is not the ordinary defeated Senate candidate. His campaign produced ripples far outside the borders of Texas, and his message resonated with Democrats nationwide.

There are two potential meanings to O’Rourke’s profile.

One is that he might have won while losing. For O’Rourke, the precedent is Abraham Lincoln. A stretch, perhaps, and an example from the Republican Party, but Lincoln lost the 1858 Illinois Senate race to Stephen A. Douglas only to win the GOP presidential nomination two years later and to enter the White House in 1861.

But there is a deeper significance here, and it redounds to the stereo struggles that the two major parties are undergoing:

How far to their relative extremes do they go — the Democrats to the left as they begin to consider the massive group at the starting line of the 2020 marathon, and the Republicans to the right as they contemplate how much they want their party to reflect the values, policies and impulses of Donald Trump and how much they want, in the post-Trump era, to return to their traditional values and positions on issues ranging from the deficit to trade to international engagement?

In short, are the Democrats in a 1972 moment, when they had to decide how much to embrace the George McGovern notions of a come-home-America foreign policy?

Meanwhile, are the Republicans in an 1841 moment, when they were in the position of the Whigs when forced to confront the uncomfortable fact that they had four years of John Tyler to contend with after the death of William Henry Harrison?

In the campaign leading to this month’s midterm elections, the Republicans embraced the president because they recognized he had a constituency that was passionate and, moreover, that his base was roiled into action by the Democrats’ response to the nomination of Judge Brett Kavanaugh to the Supreme Court.

But beneath the GOP surface there remains deep unease about the president, potent as he is as a political pugilist.

And just as significant, beneath the Democratic surface there remains deep unease about the party’s future, with virulent anti-Trump Democrats leaning left and with others following the more soothing O’Rourke model — pioneered by Rep. Seth Moulton of Massachusetts and replicated by Rep. Conor Lamb of Pennsylvania, who has won two contests in seven months.

Do the Republicans embrace the Trump model for their future? Do the Democrats embrace the O’Rourke model — unabashedly liberal, to be sure, supporting gun control, a higher minimum wage, stronger antitrust measures, but not alienating to moderates — for their future?

The Democrats’ dilemma came into sharp relief last week, for within a telling 24-hour period newly elected left-leaning Rep. Alexandria Ocasio-Cortez of New York spoke to environmental activists at a sit-in at the offices of likely House Speaker Nancy Pelosi, and the centrist Progressive Policy Center released a survey it said showed “the surprising resilience of America’s pragmatic political center.”

A century ago, Republicans split between the William Howard Taft pragmatists and the Theodore Roosevelt progressives. “Parties go through this kind of thing,” said historian Patricia O’Toole, a Columbia University professor emerita. “Eventually they have to decide.” Eventually they do.