October has been a clarifying month. The first Democratic debate exhibited Hillary Clinton’s competence and reassured the Democratic Party elite that she remains a formidable candidate. In addition, it helped chase two also-rans -- Jim Webb and Lincoln Chafee -- from the primary and appears to have breached the porous borders of Sen. Bernie Sanders’ support.

This week, Vice President Joe Biden’s retreat from the field ratified Clinton’s commanding position, freeing up funds and quashing a distraction in the news media. Then the much-anticipated House Benghazi hearing unfolded.

After two Republicans recently acknowledged the Benghazi committee’s partisan agenda -- roughing up Clinton -- the Republicans on the panel had extra incentive to appear decorous and sober. A couple managed. Others played the role of barking seals at a dystopic Sea World, spinning bright conspiracies on their noses in hopes of being tossed a kipper from the fringe. If the goal was to soften the hard feelings some Democrats hold against Clinton, Republican pride must be swelling at the committee’s resourcefulness.

With a month of drama behind us, Clinton’s status is back to where it was many months ago: She is on track to win her party’s nomination without enormous difficulty. Republicans still hope to derail her candidacy, with high hopes that scandalous emails will be the new deus ex machina. Barring that, they hope that those Democrats and Independents who’ve never warmed to Team Hillary will remain resistant right through November, 2016.

Perhaps the emails, which are trickling out in regular intervals, will fatally damage Clinton some way, somehow. But it seems unlikely. In which case Clinton will simply be a competent Democrat running for president in the mainstream of her party, supported by an incumbent president who is very popular with Democrats and sustaining credible overall favorable ratings in an angry, polarized environment. In other words, Clinton will be running with all the structural advantages that would accrue to any competent mainstream Democrat in 2016.

As each month passes without GOP inroads to Hispanic or Asian voters, the Republican demographic conundrum looms. The party seems incapable of attracting new nonwhite voters without alienating old white ones. Jeb Bush is arguably the only viable Republican who can make a credible appeal to Hispanic votes, and he has a rough path ahead. (How easy would it be for Marco Rubio to switch his stand on immigration for a second time, with political expediency again being the obvious, overriding motivation? Not very.)

Obama won a 5 million-vote margin of victory in 2012 with the same share of the white vote, 39 percent, that condemned Michael Dukakis to defeat in 1988. The 2012 electorate was 72 percent white; in 2016 it will be closer to 70 percent. (Rubio pollster White Ayres predicts it will be 69 percent.) Clinton can fall short of Obama’s share of black or Hispanic votes and still win the presidency. If she falls a bit short on both -- and right now there’s no particular reason to believe she will -- and yet does better than Obama with white women, which seems eminently plausible, she can replicate or exceed Obama’s victory.

Republicans are hoping that demography is not destiny. An economic downturn would help their cause. Barring that, however, it will likely require more than generic resistance to giving one party a third term in the White House, or liberal unease over Clinton, to alter the dynamics. When the partisan lines of the election are drawn, liberals will almost certainly vote for the Democrat.

Without a downturn, one of three conditions would have to prevail:

1. A Republican nominee of extraordinary talent and reach -- a conservative Obama.

2. A Clinton implosion due to scandal or health or unforeseen events.

3. A Republican campaign of such relentless negativity that it drives down turnout, enabling the GOP’s older white base to outperform and tilt the election.

There is no Republican Obama on the horizon, though Rubio might approximate one. A Clinton implosion is surely possible, but doesn’t seem especially likely. And there are real risks, for a party increasingly defined by anger, negativity and intemperate attacks, to running a scorched earth campaign for the White House.

So not only is Clinton back where she started, so is the GOP. The party is no closer to gaining Hispanic, Asian or black votes than it was in 2012. (Spanish media has been highlighting Republican anti-immigrant tirades for months.) Meanwhile, the elderly white share of the electorate -- the Republican base -- continues to shrink.

Bernie, Biden and Benghazi have been fun, but they’ve done nothing to alter the demographic dynamic of 2016. And Republicans appear no more prepared to answer the challenge.  

By Francis Wilkinson

Francis Wilkinson writes editorials on politics and domestic policy for Bloomberg. He was previously executive editor of the Week. -- Ed.