Photo: Michael Brochstein/Echoes Wire/Barcroft Media via Getty Images

Cory Booker endorsed Joe Biden for president in a tweet on Monday, saying the former vice president will "show there's more that unites us than divides us."

Why it matters: Booker's approval is yet another endorsement for Biden from a former presidential candidate and the second from a black competitor for the White House. Sen. Kamala Harris endorsed the former vice president on Sunday.

Details: Booker and Harris are expected to appear with Biden at a rally in Detroit, just hours before Michigan holds its delegate-heavy primary on Tuesday, the New York Times reports.

  • Booker will also campaign with Biden in Flint, Michigan, and attend a fundraiser with him earlier in the day.

The big picture: Biden has gained endorsements from at least 10 former candidates, including Harris, Pete Buttigieg, Amy Klobuchar, Beto O'Rourke and Mike Bloomberg.

  • Bernie Sanders has so far received endorsements from former candidates Marianne Williamson and Bill de Blasio.

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18 mins ago - World

Nuclear free-for-all: The arms control era may be ending

Illustration: Aïda Amer/Axios

The mushroom clouds over Hiroshima and Nagasaki have remained unreplicated for 75 years in part because the U.S. and Soviet Union — after peering over the ledge into nuclear armageddon — began to negotiate.

Why it matters: The arms control era that began after the Cuban Missile Crisis may now be coming to a close. The next phase could be a nuclear free-for-all.

Pelosi, Schumer demand postmaster general reverse USPS cuts ahead of election

Schumer and Pelosi. Photo: Alex Wong/Getty Images

House Speaker Nancy Pelosi (D-Calif.) and Senate Minority Leader Chuck Schumer sent a letter to Postmaster General Louis DeJoy on Thursday calling for the recent Trump appointee to reverse operational changes to the U.S. Postal Service that "threaten the timely delivery of mail" ahead of the 2020 election.

Why it matters: U.S. mail and election infrastructure are facing a test like no other this November, with a record-breaking number of mail-in ballots expected as Americans attempt to vote in the midst of a pandemic.

2 hours ago - Science

CRISPR co-discoverer on the gene editor's pandemic push

Photo illustration: Aïda Amer/Axios. Photos: Brian Ach/Getty Images for Wired and BSIP/UIG via Getty Images

The coronavirus pandemic is accelerating the development of CRISPR-based tests for detecting disease — and highlighting how gene-editing tools might one day fight pandemics, one of its discoverers, Jennifer Doudna, tells Axios.

Why it matters: Testing shortages and backlogs underscore a need for improved mass testing for COVID-19. Diagnostic tests based on CRISPR — which Doudna and colleagues identified in 2012, ushering in the "CRISPR revolution" in genome editing — are being developed for dengue, Zika and other diseases, but a global pandemic is a proving ground for these tools that hold promise for speed and lower costs.