Well-wired Democrats say that the massive 2020 primary field means that the nominee may still be unclear when Democrats head to Milwaukee for their mid-July convention.

• "In this new political environment and with changes in technology, there are fewer barriers to entry for candidates to enter and remain in the race," said Doug Sosnik, former White House political director for President Clinton.
• "These changes encourage more candidates to enter the race and stay in longer."

Why it matters, per Sosnik: "[A]ll these factors ... leading up to March 17 [Arizona, Florida, Illinois primaries] are the reasons that we could have the first brokered convention since the political reforms and the advent of the modern presidential primary system that were enacted after the chaotic 1968 convention in Chicago."

• What to watch for: By March 17, 70% of the delegates will have been selected. Sosnik says that's when we'll know if the nomination is heading toward conclusion, or a brokered convention.

Jennifer Palmieri, former communications director for President Obama and Hillary Clinton, expects a "long primary ... wild ride," with "fewer barriers to getting in early and staying in late, till at least Super Tuesday."

• Be smart: "That could change," Palmieri added, "if something unexpected happens and a candidate not seen as viable comes out on top in Iowa and/or New Hampshire, and candidates who are not doing well feel the need to get out to throw support behind a consensus candidate."

Go deeper: See Doug Sosnik's memo breaking the Democratic nominating fight into six phases, and his six slides showing the accompanying calendars.

Joe Biden will officially launch his presidential campaign in Philadelphia this afternoon by arguing that President Trump is dividing the country on race, religion, ethnicity and sexual orientation, Axios' Alexi McCammond reports.

• According to the campaign, Biden will say we need a president for everyone — not just Trump's base. And the former vice president will ask voters to choose unity (Biden) over division (Trump).
• The campaign expects 2,000 people for the downtown rally at Eakin's Oval. Kamala Harris' campaign said 20,000 people attended her kickoff in Oakland.

Why it matters: Biden's focus on Trump fits the general election strategy he's been running all along — and it baits the president to continue attacking him.

• What to watch: Trump is holding a rally in Montoursville, Pa., on Monday to support Fred Keller, a GOP congressional candidate who has a special election on Tuesday. Look for the president to mention Biden at least once.

Sneak peek ... From Biden's prepared remarks:

If the American people want a president to add to our division, to lead with a clenched fist, closed hand and a hard heart, to demonize the opponents and spew hatred — they don’t need me.

They already have a President who does just that. I am running to offer our country — Democrats, Republicans and Independents — a different path.

A new poll from LeanIn.org and SurveyMonkey found that 60% of male managers are uncomfortable taking part in workplace activities like mentoring and socializing with junior-level women — a 32% increase from last year, Axios' Orion Rummler writes.

• Why it matters: Women can receive less support and development in their careers — and have fewer chances to prove themselves in the workplace — as men in leadership positions pull back in the wake of the #MeToo movement.

By the numbers: The poll by Lean In, founded by Facebook COO Sheryl Sandberg, found that 36% of men say they've purposefully avoided mentoring or socializing with a woman because they were "nervous about how it would look."

• 70% of employees said their company has "taken action to address sexual harassment," a 46% increase from last year.
• Half of polled employees say punishments for sexual harassment are not harsh enough.

Go deeper.

In El Paso, migrants walk yesterday while being detained by Border Patrol after crossing to the U.S. side of the U.S.-Mexico border barrier.

"If a fetus is a person, it should get child support, due process and citizenship," Carliss Chatman of Washington and Lee University School of Law writes on the cover of tomorrow's WashPost Outlook:

• The argument: "The logic of Alabama’s abortion law should permit you to claim a fetus on your taxes and collect insurance if you miscarry."
• Why it matters: "Trying to define citizenship and personhood based on the laws of each state creates some far-fetched and even ridiculous scenarios. If we follow that logic, we’ll tie our Constitution into a knot no court can untangle."

Grumpy Cat, whose sourpuss expression entertained millions on the internet and spawned hundreds of memes, national television commercials and even a movie, died at age 7, AP reports:

• Her owners posted on social media that she experienced complications from a urinary tract infection. "She passed away peacefully on the morning of Tuesday, May 14, at home in the arms of her mommy, Tabatha," they wrote.
• Why Grumpy mattered: "Grumpy Cat has helped millions of people smile all around the world — even when times were tough," her owners said.

The cat's real name was Tardar Sauce and the owners were never sure what her breed was.

• Her website said her grumpy look was likely because she had a form of feline dwarfism.
• She rose to fame after her photos were posted on Reddit in 2012.
• Grumpy Cat had more than 8 million followers on Facebook, 2.5 million on Instagram and more than 1.5 million on Twitter.