Along with helping Democrats unite behind Hillary Clinton as their presidential candidate, there’s another role party leaders hope Bernie Sanders will embrace this fall: helping elect Democratic candidates down the ballot.

Yet throughout the primary season, Sanders has limited such assistance to just a handful of congressional and local progressives who occupy his wing of the party, while Clinton has raised vast sums of money to help party committees boost countless other candidates.

Democrats see a potentially powerful role for Sanders in helping congressional candidates across the country as they push to regain control of the Senate and make major gains in the House, especially given the passionate following he generated during a spirited primary run. But the independent senator from Vermont has yet to indicate whether he’s interested in that role.

There are several ways Sanders can be helpful to Democrats running local or congressional races, such as pushing his supporters to back certain candidates through endorsements and generating excitement through rallies later in the cycle. But most Democrats point to one specific way Sanders can help most: fundraising. He raised and spent more than $200 million on his presidential campaign, the vast majority of it through small-dollar donations. He didn’t accept super PAC assistance, and on the stump he often asked supporters to donate just $27, well below any maximum contribution limits.

The few times Sanders has used that power for another candidates’ benefit, it has netted big money. Tim Canova, who is challenging Democratic National Committee chair Debbie Wasserman Schultz in her Florida district primary, raised $250,000 off just a single fundraising email from Sanders.

He also helped Nevada congressional candidate Lucy Flores generate more than $600,000. Yet that fundraising support showed its limitations Tuesday: Flores lost by double digits to state Sen. Ruben Kihuen, who was backed by Senate Minority Leader Harry Reid, a wielder of tremendous influence in the Silver State.

Sanders has also raised money for former Sen. Russ Feingold in his Wisconsin race; Zephyr Teachout, a progressive House candidate in New York; Washington state’s Pramila Jayapal; and eight state legislature candidates in seven states.

The Sanders model so far has been to back candidates who backed his presidential bid, and he has yet to branch out to other party members across the country. But Democrats aren’t concerned about that just yet – almost across the board, they assume he’ll be there to help.

Reid said after a meeting with Sanders last week that he’s “going to be good for my senators that are running, those that are here and new ones that are going to be here real soon. I’m confident he will be a good campaigner for Democratic senators and the Democratic [presidential] nominee.”

Sen. Chuck Schumer, who is expected to be the party’s next leader in the Senate after Reid retires at the end of this term, held his own meeting with the runner-up to Hillary Clinton last week, and echoed Reid’s comments.

“He cares a lot about the Senate majority becoming Democratic, but he also cares about keeping his people engaged and the way to do that is issues,” Schumer said. “On issues, so many issues, the Democratic caucus and Bernie Sanders are aligned.”

That wasn’t always the case. Though he caucused with Democrats, Sanders billed himself as an independent – until he declared his candidacy for president.

The former Burlington, Vt., mayor has yet to say whether he will actively raise money or campaign for Democratic candidates this fall. But in late March, when MSNBC’s Rachel Maddow asked point-blank whether he would at some point turn his fundraising prowess toward helping the party more broadly, Sanders didn’t commit.

“We’ll see,” he said. “Right now, again, our focus is on winning the nomination.”

It was just several weeks after that interview that Sanders started raising money for that handful of candidates. Multiple requests for comment from his campaign were not returned.

After Sanders visited with his conference colleagues Tuesday for the first time in months, Sen. Jon Tester, the chairman of the Democratic Senatorial Campaign Committee, said he requested – and Sanders agreed to – a short meeting in the near future to discuss a campaign role. “He absolutely will” be helpful, Tester said.

“Bernie’s always been very, very good helping us when we’ve asked,” the Montana lawmaker said earlier this month.

Sanders’ close allies also expect him to work hard at helping elect other Democrats in the fall. Rep. Keith Ellison, the first member of Congress to endorse Sanders’ presidential bid, said the two-term senator is excited about the potential role. Ellison emphasized the importance of Democratic candidates raising money in the way Sanders did, through small-dollar donations, and highlighted the differences between voters who max out and voters who donate in small amounts.

“So many of us around here, the incentives are to chase the max-out donor, but the max-out donor has got, not always, but often has a different set of priorities than the $27 donor,” Ellison told RealClearPolitics in an interview. “One is concerned about the minimum wage, one is concerned about other stuff. I’m not saying that max-out donors are not wonderful, genuine people and that some of them don’t worry about the middle class, but the truth is it’s just different life experiences at some point."

Sen. Sherrod Brown, a progressive from Ohio who is close with Sanders, said his colleague would be helpful in fundraising, generating excitement, and getting young people involved in down-ballot races. Ohio has one of the most competitive – and likely most expensive – Senate races in the country, between GOP incumbent Rob Portman and former Democratic Gov. Ted Strickland.

“I think [Sanders] will help get out the vote,” Brown told RCP. “I think he will help support progressive candidates like Ted Strickland. I have no doubt. I’m fully confident Bernie will be there in a big way for the top of the ticket and for Senate candidates."

More than just the fundraising, however, Sanders was able to generate extreme excitement for his candidacy, with tens of thousands of people attending rallies for him across the country. In particular, Sanders drew support from young people, who generally vote in much lower numbers than other age groups. Because they tend to lean Democratic, their participation is critical to Democrats’ success this fall.

Achim Bergmann, a veteran Democratic strategist who previously worked for the DCCC, said it isn’t clear this early whether Sanders hosting rallies would actually be helpful or harmful. For example, rallies in the heavily liberal Madison area of Wisconsin would likely boost Feingold in his race against Sen. Ron Johnson, but he pointed to Rep. Rick Nolan of Minnesota, a client of his, as a case in which Sanders’ presence would be helpful in certain parts of the district but harmful in others.

“That’s a long way away and a lot’s going to happen between now and October,” Bergmann said. “The money has an impact no matter what."

Democrats believe that with Donald Trump at the top of the GOP ticket, they have Republican incumbents are on their heels and are poised to take back the Senate and make significant gains in the House. They say Sanders can be a big part of that, but Bergmann said his strategy concerning which candidates to assist will have to change to make a difference.

“We have a real opportunity to win back a lot of seats in the House, maybe get close to the majority, maybe even win the majority,” Bergmann said. “His network can be extremely helpful in that, but that’s not going to be won by picking progressives over other Democrats in primaries or helping progressives in a race that’s unwinnable."

Still, Rep. Ben Ray Lujan, the chairman of the DCCC, said earlier this week he’s confident that the millions of supporters who voted for Sanders in the primary will be there for other Democrats in November.

“I think it’s critically important that we earn the trust of every one of Sen. Sanders’ voters and supporters to come our way,” Lujan said. “I would argue with you that they’re already there. … On issue after issue, Democrats overall, up and down the ballot, are on the side of where Sen. Sanders supporters are."