WASHINGTON — At some level, President Donald Trump hit the nail on the head in his response to Sen. Elizabeth Warren, D-Mass., releasing a DNA report on Monday that shows that a small fraction of her ancestors were Native American.

"Who cares?" the president asked at the White House.

Of course, it's Trump who has appeared to care most: He's repeatedly mocked Warren's claim of Native American heritage — at campaign stops, at an official White House event honoring Native Americans and on Twitter, bestowing the derisive sobriquet "Pocahontas" on her.

"(Democrats have) gone so far left they consider 'Pocahontas' to be a rational person. Elizabeth Warren, I hope she runs. We can finally get down to the fact whether or not she has Indian blood," Trump said at a rally in Council Bluffs, Iowa, last week. "So far she's not doing too well, her mother says she has high cheekbones, and she's gotten so many advantages."

But few other people actually care. Voters aren't going to pick Warren, or decide against her, based on whether they believe she has Native American heritage.

The potential damage to her lies in Trump's basic argument that Warren abused minority-preference systems to get university teaching jobs. This allegation, which The Boston Globe deemed unfounded after a thorough investigation, works both with Republicans and with some Democrats for the same reasons: It portrays Warren as a fraud and it undermines affirmative action.

And that's why Warren, who has all but announced her candidacy for the presidency, had to address it in a way that gives her supporters a talking point to push back on both Trump and the Democratic rivals who will whisper — if not outright say — that she's pretended to be a minority to benefit herself without suffering discrimination.

She rolled out the DNA report with a video in which she talks with her three older brothers — all Republicans — about their family history.

"She needed to deal with the ancestry issue head on and put it behind her," said Pennsylvania Rep. Brendan Boyle, who, at 41, is among the younger members of the House Democratic Caucus. "This video accomplishes that. Going forward, I think she should do more of her in Norman, Oklahoma, with her family."

For both Trump and Warren, who prides herself on populist authenticity amid political poppycock, this fight is about whether she is honest and whether she is strong enough to stand up to knock him out of the presidency.

His ridicule of Warren, like his ridicule of all past, current and future rivals, is about him asserting that he's in the dominant position — that he is tougher than whomever he is trying to diminish. The fact that Trump goes after Warren is a sign that he thinks she's a viable contender.

That's where the constitution of her spine — iron or mercury — matters to potential primary voters more than the makeup of her chromosomes.

With Trump hammering her on the campaign trail — at stops ostensibly about the midterms, but in reality more about Trump's 2020 re-election effort — Warren had to decide whether to keep quiet until after voters go to the polls or essentially launch her campaign before the traditional post-midterm period.

Warren opted against waiting — and some Democrats, in a partisan mirror image of the complaints some Republicans have of some Trump attacks on the trail — did question the timing.

"Argue the substance all you want, but why 22 days before a crucial election where we MUST win house and senate to save America, why did @SenWarren have to do her announcement now?" tweeted Obama 2012 campaign manager Jim Messina. "Why can't Dems ever stay focused???"

But her choice to release her DNA report should be taken in context with the five-plus-minute video and a Washington Post report about the work she's done on behalf of Democratic candidates up and down the ballot across the 50 states during the midterm election cycle. That is, it's a piece of an overall shadow campaign rollout that has allowed Warren to put forward her message on her strengths and weaknesses.

In his book "Hardball," MSNBC's Chris Matthews advised candidates to "hang a lantern on your problems" the way John F. Kennedy did when he talked about his Catholicism, and his refusal to take orders from the Vatican, at a time when his religion was viewed as a weak point for him with voters.

In talking about her DNA, Warren has done just that. And she's trying to turn the weakness into a strength by hitting Trump on his promise to donate $1 million to a charity of her choice if she could prove she had Native American ancestry — a vow he said Monday that he'd never made despite the video evidence to the contrary.

Having some memory problems, @realDonaldTrump? Should we call for a doctor?



Here’s something you won’t “forget,” Mr. President: You’re the least popular president in modern history & your allies will go down hard in the midterm elections. 22 days. Tick-tock, tick-tock. pic.twitter.com/53FV0HXGXX — Elizabeth Warren (@elizabethforma) October 15, 2018

Perhaps the biggest challenge for the many Democrats seeking the presidency in 2020 is to show voters that they can go toe-to-toe with Trump without changing their own brands or sounding completely off-kilter. It's a conundrum that confounded all of Trump's Republican primary rivals in 2016 — remember Marco Rubio imploding as he made fun of the size of Trump's hands? — along with Democratic nominee Hillary Clinton.

Democrats' search for the candidate who can pull it off will be at the heart of their nominating contest. On Monday, Warren began to make her case that she's the one.