DES MOINES — Senator Cory Booker of New Jersey did not announce he was running for president on Saturday. Nor did he say he was thinking about it. But on a demoralizing day for Democrats, he came to this bellwether state and sounded a lot like someone who wanted to lead the Democratic Party in its quest to oust President Trump from the White House.
Just hours after the Senate voted to confirm Mr. Trump’s nominee to the Supreme Court, Brett M. Kavanaugh, ending a bitter confirmation battle that laid bare the divisions in the country, Mr. Booker stood before a rapt audience at the Iowa Democratic Party’s annual fall gala and offered a theme of resilience and hope.
“It is not a time to give up, it’s a time to get up, to rise up, to speak up,” he said. “It’s time for you not to wait for hope, but to be the hope.”
Mr. Booker condemned Mr. Trump for mocking Christine Blasey Ford, the woman who had accused Judge Kavanaugh of sexually assaulting her.
“We’re not defined by a president who mocks a hero, Dr. Blasey Ford,’’ he said. “We’re not defined by a president who does not believe women. We’re going to be defined when this state not only says that we believe women, but we elect women.”
Mr. Booker had to stay in Washington for a late-afternoon vote on the confirmation of Judge Kavanaugh, and there was some question about whether he would arrive in time.
Republicans quickly reacted to his appearance on Saturday. As the fête was beginning, the state’s Republican Party blasted out a news release calling Mr. Booker an “East Coast Grandstander” and warning against his “brand of resistance.”
It is a ritual of politicking for presidential hopefuls to swing through this early-voting state, whose reputation as a political bellwether draws an array of potential candidates — or anyone who hopes to be seen as one — long before any election is to take place. Eric Garcetti, the mayor of Los Angeles, spent two days here in April, talking to union carpenters, activists and firefighters. Michael Avenatti, the lawyer for Stormy Daniels and an anti-Trump crusader, stormed into the state in August to declare he might run for president in 2020.
Even lesser-known politicians have descended on the state. Representative John Delaney of Maryland has campaigned in all of Iowa’s 99 counties, saying his lack of name recognition has forced him to get an early start.
As the midterm elections approach, other possible 2020 candidates, including Senator Elizabeth Warren of Massachusetts and former Vice President Joseph R. Biden Jr., are also fanning out across the country — to campaign for midterm candidates but also to get themselves in front of voters. Senator Kamala Harris of California is in Ohio this weekend, where she is keynoting the Ohio Democratic Party’s state dinner.
The flood of candidate appearances is a sign of just how crowded the field of Democratic candidates could be heading into 2020, and how aggressively they will make the case that they are better than President Trump. Energized anew by a bitter Supreme Court confirmation process, many Democrats are looking for a leader who can offer a different vision for the country, and fight back against an administration they see as reckless, toxic and hostile.
Last weekend, Ms. Warren gave the strongest signal yet that she would be a candidate, saying she was taking “a hard look” at a 2020 run because the “broken government” needed to be fixed.
Mr. Booker’s trip to Iowa, his first since he campaigned in the state for Hillary Clinton in 2016, followed recent campaign stops in Texas, Georgia and Florida, all of which have tight races whose outcomes could shift the momentum for the Democrats. Mr. Booker, who has family in Iowa, will also be in the state on Monday for a get-out-the-vote rally. (His family is throwing him something of a family reunion on Sunday, according to an aide.)