Part 4 in a series

Democrats eying a potential White House run in 2020 have been eager to lend their star power to party candidates up and down the ballot in this year’s midterm elections. The nominal goal is to strip Republicans of their majority on Capitol Hill, but the clear secondary goal is to help these likely presidential contenders build up their own profiles and establish networks ahead of an Oval Office bid.

Sens. Kamala Harris of California and Cory Booker of New Jersey aren’t on the ballot this year, but they have been busy on the 2018 campaign trail stumping and raising money for Democratic candidates. Sens. Elizabeth Warren of Massachusetts, Bernie Sanders of Vermont, and Kirsten Gillibrand of New York are managing their own relatively easy re-election races while traveling around the country on behalf of federal and local candidates.

Former Vice President Joe Biden has also waded into the fray, and is planning to campaign this fall in swing states crucial to winning the presidency. Maryland Rep. John Delaney, who announced his long-shot presidential campaign last year, endorsed 22 candidates for office in Iowa this month and backed 20 New Hampshire candidates in July.

Delaney lacks the name recognition of his better-known colleagues, and so endorsements can serve as a way to establish a presence and make connections in the early-voting states. As for the others, activity on the midterm campaign trail is a demonstration of their fundraising prowess and ability to build a constituency around key issues and ideas.

"Creating a network matters more than winning or losing,” says New York Democratic strategist Hank Sheinkopf. Candidates know that “people don't forget who was with them at the time of their greatest need.”

Such campaign activity also is an audition of sorts, demonstrating the level of seriousness with which potential candidates are approaching presidential bids, and sending signals to party power brokers and voters about their viability.

“The top 2020 Democratic contenders have an opportunity during the midterms to demonstrate what type of coattail effect they can have at the top of a ticket in two years,” says party strategist Joel Payne. “The organizing grassroots of the Democratic Party will be looking at these 2020 contenders between now and November 2018 to determine who has organizing and fundraising muscle, who can turn out big crowd and register voters, who can challenge President Trump and excite the base with the greatest impact.”

The midterms also provide opportunities for 2020 candidates to identify with up-and-comers in the party. Stacy Abrams of Georgia, for example, could become the nation’s first black female governor if elected in November, and has earned the endorsement of several potential presidential contenders.

Abrams is one of over 20 candidates Harris has backed, a list that includes Senate colleagues but also aspirants for local offices. Harris has raised over $5 million for candidates and has traveled to more than a dozen states to campaign. Other notable candidates she’s backed include former NAACP president and Maryland gubernatorial hopeful Ben Jealous, Atlanta Mayor Keisha Lance Bottoms, and Baltimore State’s Attorney Marilyn Mosby.

Warren, who included Abrams in a list of over 60 candidate endorsements, has campaigned in seven states and given $5,000 to each of the 50 state parties. Warren has also contributed $210,000 to the Democratic Senatorial Campaign Committee, and given maximum contributions to the House campaign arm and the DNC. In addition, the Massachusetts senator has focused her campaign contributions on redistricting efforts, giving to nine targeted state campaigns as well as the National Democratic Redistricting Committee and the Democratic Legislative Campaign Committee. Last week, Warren unveiled a government reform bill that hits on anti-corruption themes critical to the party’s midterm messaging.

Gillibrand has focused her midterm efforts on female candidates. Her Off the Sidelines PAC has endorsed over 50 women running for office, and the New York lawmaker has taken risks to endorse candidates in contested primaries -- with a great degree of success.

Sanders has an expansive grassroots network from his presidential run, but his track record in primaries has been lackluster, raising questions about his continued influence. But the senator and his supporters argue that ideas he has long championed — including “Medicare-for-all” and a $15 minimum wage — have become mainstream in Democratic politics. And on Tuesday, the candidate he backed in the Florida governor’s race, Tallahassee Mayor Andrew Gillum, pulled off an upset win for the Democratic nomination. (If victorious over Rep. Ron DeSantis in November, he would become the state’s first African-American governor.)

"The pre-[presidential] primary period is tricky one; you want to be encouraging enthusiasm for a run while not openly soliciting it.” Democratic strategist Erik Smith

As one of the few old-guard members of the party who still resonates with portions of the electorate, Biden has been a vaunted surrogate on the midterm campaign trail. The former vice president has endorsed nearly 30 candidates this cycle, including key party recruits and rising stars such as Rep. Conor Lamb in Pennsylvania and congressional hopefuls Brendan Kelly in Illinois and Mikie Sherrill in New Jersey. Biden’s midterm campaign schedule is expected to look more like a presidential campaign swing, hitting key states such as Florida, Nevada, and Michigan, according to The Hill.

“Most candidates don't want to get out ahead to the cycle and need to figure out how to build relationships and goodwill in early primary states to ensure they have every advantage,” says Democratic strategist Erik Smith, an Obama campaign veteran. “The pre-[presidential] primary period is tricky one; you want to be encouraging enthusiasm for a run while not openly soliciting it.”

While campaigning for candidates in the midterms is a tradition among presidential hopefuls, Smith says this cycle is uncovering new power centers in the party.

“This year is creating stars that didn't exist before,” says Smith, referring to candidates such as Alexandria Ocasio-Cortez in New York or Beto O’Rourke in Texas. “There are House and Senate candidates who will be bigger celebrities than those candidates [preparing a presidential run]. Winning their support may be more important.”

Democratic operatives argue that Donald Trump’s presidency has helped to bolster opposition activists and candidates, thus expanding the network White House hopefuls can tap. “Even if [rising stars] lose, they are bound to be involved in politics for a while,” says Smith. “Those relationships matter a lot. Making investments in those relationships will have payback decades down the road.”