TEMPE, Ariz. — Julian Castro aimed for a national breakout Thursday during a televised Fox News town hall, hammering President Donald Trump while ignoring his many Democratic presidential rivals.

In a town hall taped against the backdrop of Tempe Town Lake and before an audience of Republicans and Democrats, the former secretary of Housing and Urban Development under President Barack Obama and a former mayor of San Antonio repeatedly lashed out at Trump while also highlighting his stance on a range of topics including abortion rights and police force.

He also rebuffed multiple attempts by Fox News moderators Bret Baier and Martha MacCallum to talk about this Democratic rivals, instead focusing his energy on the sitting president.

Early on, Castro attacked Trump for saying he would accept opposition research on a political opponent from a foreign government. Years from now, Castro said, "We’re going to look back on this as Americans, not as Republicans or Democrats, or liberals or conservatives, and say, ‘What in the hell is wrong with that president?’”

That line drew the first of many rounds of applause.

Later, Castro pushed back when asked how Trump’s comment is different from those made by Hillary Clinton’s 2016 presidential campaign’s press secretary. Clinton’s adviser was quoted in an October 2017 Washington Post story as saying he would be willing to pass opposition research to reporters and travel abroad to verify information.

Castro repeatedly brushed off attempts by the hosts to answer for the policies or comments of other candidates. At one point, he said he did not understand why Fox was still focused on Clinton, the 2016 Democratic nominee.

“Hillary Clinton is not on the ballot,” he said.

During a contentious moment near the end of the town hall, when asked about former Vice President Joe Biden’s reversal on the Hyde Amendment that restricts federal money for abortions, Castro said he didn't want to talk about rival candidates "when the fact is, I need to introduce myself to a lot of people ... I don’t want them to know what Joe Biden stands for — I want them to know what Julian Castro stands for."

The site of the event, Tempe, reflected Arizona’s expected importance in the 2020 presidential election and Castro’s hopes to connect with the state’s shifting political demographics.

Castro looked to use the town hall as a platform to make the case to a conservative television audience that his experience as a mayor makes him a good fit for the White House.

As mayor, he said, he had to confront issues that touch people’s lives in meaningful ways, from addressing police shootings to forging relationships and balancing budgets.

As president, Castro said he would work with allies to deescalate tensions with Iran, lead an overhaul of the nation’s immigration system and enact legislation to try to reduce excessive use-of-force by law enforcement.

To applause, Castro reiterated his support for abortion rights and for Roe v. Wade, the landmark Supreme Court ruling that legalized abortion. He said he would nominate judges who share that view.

Castro also outlined his proposal to establish national standards to prevent unnecessary force by police officers, ticking off the names of lives lost by deadly force. When he got to the name of Antonio Arce, the 14-year-old shot by a Tempe police officer, the crowd burst into applause.

“The system itself is broken and we need to fix it,” he said.

Arce was shot between the shoulder blades while running away from an officer. Tempe police have said the officer, who was responding to a vehicle burglary, saw the teen holding a gun in a truck before he fled. It was later determined to be an airsoft gun. The shooting is under criminal review and administrative review; the officer has resigned from the city’s police force.

Castro is one of 23 Democrats seeking the party’s nomination to challenge Trump in 2020 and, on Thursday, was among the 20 contenders in the wide-open field who will be allowed to participate in the first round of Democratic primary debates.

Even so, Castro remains a long shot, drawing about 1 percent support in many Democratic polls.

“No one is either going to win or have a following by just being who they are,” Arizona-based Democratic consultant Andy Barr said of the field. “They’re going to have to really perform. There’s about 20 candidates right now who have done nothing to build up a base of support, and that includes Castro.”

Barr said Castro needs a game-changer on the debate stage: “He has to do something in these debates coming up, otherwise he’s toast.”

The Republican National Committee, meanwhile, said Castro was in the wrong place with the wrong ideas.

“From his support of sanctuary cities, socialized health care, and a 70-percent income tax, Julian Castro is completely out of touch with Arizona values,” RNC spokeswoman Samantha Zager said in a written statement ahead of the event. “Voters in the Grand Canyon State know that President Trump has secured the border, brought jobs to the state, and kept more of their money in their own pockets. Castro will have a tough time selling his far-left policies in a state that is thriving under President Trump’s administration.”