Sen. Bernie Sanders, former Vice President Joe Biden, Sen. Elizabeth Warren and South Bend Mayor Pete Buttigieg at the Oct. 15 Democratic Presidential Debate at Otterbein University in Westerville, Ohio. Photo: Chip Somodevilla/Getty Images

A clear top tier is emerging in the 2020 Democratic race — but the likely eventual nominee is far from certain, an ABC News/Washington Post poll published early Sunday shows.

Why it matters: Per the Washington Post, the race is "competitive and fluid less than 100 days before the Iowa caucuses, with a stable trio of leading candidates" — the frontrunner, former Vice President Joe Biden (27%); Sen. Elizabeth Warren (21% ); Sen. Bernie Sanders (19%); and fourth-placed South Bend Mayor Pete Buttigieg (9%) breaking away from other single-digit rivals.

  • About half of Democrats polled who support a candidate say they’d consider another one.

Worth noting: Sanders’ health is a concern for a large portion of the of 1,003 Democrats surveyed in the poll several weeks after he had a heart attack. He's vowed to run a "vigorous campaign.

  • "The poll notes that "younger adults, who are among Sanders’ strongest supporters, are most apt to think he’s in good enough health to serve — six in 10 18- to 39-year-olds say so. Just 40 percent of those age 40 and older agree."

Read the full poll:

Go deeper: The problem with 2020 presidential polls

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Updated 37 mins ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 4 p.m. ET: 12,813,864 — Total deaths: 566,790 — Total recoveries — 7,046,535Map.
  2. U.S.: Total confirmed cases as of 4 p.m. ET: 3,286,025 — Total deaths: 135,089 — Total recoveries: 995,576 — Total tested: 39,553,395Map.
  3. States: Florida smashes single-day record for new coronavirus cases with over 15,000 — Miami-Dade mayor says "it won't be long" until county's hospitals reach capacity.
  4. Public health: Ex-FDA chief projects "apex" of South's coronavirus curve in 2-3 weeks — Coronavirus testing czar: Lockdowns in hotspots "should be on the table"
  5. Education: Betsy DeVos says schools that don't reopen shouldn't get federal funds — Pelosi accuses Trump of "messing with the health of our children."

11 GOP congressional nominees support QAnon conspiracy

Lauren Boebert posing in her restaurant in Rifle, Colorado, on April 24. Photo: Emily Kask/AFP

At least 11 Republican congressional nominees have publicly supported or defended the QAnon conspiracy theory movement or some of its tenets — and more aligned with the movement may still find a way onto ballots this year.

Why it matters: Their progress shows how a fringe online forum built on unsubstantiated claims and flagged as a threat by the FBI is seeking a foothold in the U.S. political mainstream.

Lindsey Graham says he will ask Mueller to testify before Senate

Photo: Tasos Katopodis/Getty Images

Senate Judiciary Chairman Lindsey Graham (R-S.C.) tweeted Sunday that he will grant Democrats' request to call former special counsel Robert Mueller to testify before his committee.

The big picture: The announcement comes on the heels of Mueller publishing an op-ed in the Washington Post that defended the Russia investigation and conviction of Roger Stone, whose sentence was commuted by President Trump on Friday.