As Donald Trump's march toward the Republican nomination continues, so does the Republican Party's march toward irrelevance with the youngest generation of voters.

Far from turning the tide after two dismal presidential election cycles, a Hillary Clinton versus Donald Trump general election matchup would likely lead to yet another double-digit crushing blow to the GOP's candidate with this key voter demographic.

For those of us who long for a Republican Party that is competitive across generations, new polling data suggest this presidential election is shaping up to be every bit the nightmare it seems.

Young voters have been something of an afterthought during the presidential primary season. In Republican contest after contest, in state after state, voters under age 30 have comprised only about one out of every 10 who showed up at the polls. To the extent that Republicans have focused on this generation at all, it is to point and laugh at Hillary Clinton's terrible performance with this same demographic within the Democratic primary.

Yet even as Clinton loses to Bernie Sanders by four-to-one margins in Democratic primaries, don't for one second think that weakness translates into a poor showing with young voters in a general election, especially one that includes Donald Trump.

According to fresh data from the Harvard Institute of Politics' semi-annual study of young voters, 61 percent of young voters say they'd prefer Democrats hold the White House, against just 33 percent for Republicans, a 28-point advantage. And when Clinton is pitted against Trump by name, her lead widens to 36 points.

For context, a 36 point loss among voters under thirty would be slightly worse than John McCain performed against Barack Obama in 2008.

Republicans who have talked themselves into the prospect of a Trump nomination on the grounds that Trump will run up the score with older, working-class white voters are playing with mathematical fire. In 2012, Mitt Romney won voters over the age of 30, but lost the under-30 demographic by such a large margin that he lost the White House. Facing youth vote numbers like these, Trump will have to win extraordinary numbers of middle-age and senior voters to have a fighting chance.

Trump's weakness with the young isn't just a product of his terrible standing with young Latinos or African-Americans, or the way that he has turned off young independents. Yes, Trump doesn't even get out of single digits with nonwhite young voters, winning a pathetic 5 percent of black and 9 percent of young Hispanic voters. But strikingly, Trump also tanks with slices of the youth vote that ought to be friendlier to him.

Mitt Romney won young white voters in the 2012 election; Trump loses this group to Clinton. He also picks up only 29 percent of young men, with 47 percent saying they'd pick Clinton. A majority — 57 percent — of young Republicans hold an unfavorable view of their own presumptive nominee.

With such a disaster unfolding, the Republican Party's problem is no longer about trying to expand its appeal to young voters who have been skeptical of its message, policies or candidates. This poll suggests that the Republican Party may be in triage mode and not have the luxury of winning over new young voters, with significant slices of the young Republican electorate seemingly ready to defect. Forget bringing new young people into the tent; the GOP may need to build a wall around their own tent to keep young Republicans from leaving.

The Republican Party is already two bad elections deep with a large slice of the millennial generation. And that group of voters will ripple through elections for decades like the young FDR Democrats and young Reagan Republicans, casting ballots for the party that was in their favor when they first entered the political process.

Clinton was a candidate that Republicans could have defeated in a general, or at least one against which the G.O.P. could have begun to repair some of the damage wrought over the last decade. Younger voters are not, contrary to the headlines, enamored of socialism (only one-third support it) or even in love with Hillary Clinton (a majority view her unfavorably).

This was a winnable election, or at least one in which Republicans had a shot to change their fortunes and lose less badly. At least when it comes to young voters, Republicans appear intent on blowing their chance.

Kristen Soltis Anderson is a columnist for The Washington Examiner and author of "The Selfie Vote."