CHICAGO (AP) — President Barack Obama urged donors Friday to rally around Democratic candidates for the House in next month’s election, saying a stronger caucus will make the difference on such issues as immigration, rebuilding roads and bridges, and ensuring access to an early education.

Obama said he was confident of victory by Democratic presidential nominee Hillary Clinton on Nov. 8, but said she’ll need supportive members in the Republican-controlled House of Representatives to get things done. Democrats would need to pick up 30 seats to retake the majority.

“It’s an uphill battle. Nancy is the first to acknowledge it,” he said, referring to Democratic leader Nancy Pelosi of California, who was in attendance. But he said if Democrats are willing “to really bear down in this last month, if we are, as we say in church, cheerful givers, then I think we’ve got a real shot.”

Obama said his administration tackled tough issues when Democrats had the majority in both chambers of Congress during his first two years as president. Examples he cited included increasing the level of Pell grants for college students, expanding health insurance coverage and creating the Consumer Financial Protection Bureau.

“Across the board, whatever your issue, the stakes could not be higher, and I hope all of you feel that same sense of urgency,” he said.

Less than five weeks before the election, Obama returned to his hometown of Chicago to raise money for Clinton and Rep. Tammy Duckworth, who is running for his old Senate seat. His first fundraiser Friday benefited the Democratic Congressional Campaign Committee. Participants paid $10,000 and up to attend.

Obama also used the visit to cast an early ballot. Democrats have been working to encourage supporters to vote early nationwide, and Obama led by example. After speaking at the fundraiser for Democratic House candidates, his motorcade stopped at the Cook County Office Building.

He shook the hands of about a dozen poll workers and was directed to a desk where cameras watched from about 30 feet away. As Obama marked the ballot, he joked about the camera operators catching his every move. He said: “Now, they can’t see me, can they?”

Obama then attended a joint fundraiser for the Democratic National Committee and the Hillary Victory Fund. The money raised will pay for voter registration efforts and getting Democratic voters to turn out in battleground states. Participants contributed $33,400 to attend. The fundraiser took place at the home of J.B. Pritzker, who heads a private investment firm and served as national co-chairman of Clinton’s presidential campaign in 2008. The fundraiser was closed to the press.

Obama’s final fundraiser on Sunday is for Duckworth, who is trying to unseat Republican Sen. Mark Kirk.

Kirk won the Senate seat during the 2010 election that swept Democrats out of power in the House and allowed the GOP to make gains in the Senate. He faces a tougher road in a general election, when more Democratic voters cast ballots.

Most public polls suggest Duckworth is leading in the race. Democrats pounced recently when Kirk said Obama was “acting like the drug dealer in chief” after the Obama administration delivered $400 million in cash to Iran on the same day Tehran agreed to release American prisoners.

Democratic officials used the comments to tie Kirk to GOP presidential nominee Donald Trump, with a party spokesman saying that “hateful and divisive politics have taken over the entire Republican party.” Kirk is not endorsing Trump and has called him “bigoted and racist.”

The Senate race represents one of the Democratic Party’s best hopes this November. Democrats need a net gain of four seats to secure the majority if Clinton wins the presidency, as her vice president would break a tie. The party needs to net five seats if Trump wins.

White House spokesman Eric Schultz said Obama considers Duckworth a friend and he wants her in the Senate because “he thinks she’s a phenomenal public servant” and a “true patriot.”

Before winning election to the House, Duckworth served in the Obama administration as an assistant secretary at the Department of Veterans Affairs. She served in Iraq and lost her legs when her helicopter was hit by a rocket-propelled grenade. She spent the next year recovering at the Walter Reed military hospital in Washington.