Former San Antonio Mayor and Obama administration official Julian Castro formally announced he’ll run for the Democratic presidential nomination in 2020, attempting to get an early jump on what’s shaping up as a crowded field of candidates.

Castro has been considered a rising star in the Democratic Party — he was a contender to be Hillary Clinton’s running mate in 2016 — but he’ll be entering a race that’s likely to include candidates with higher national profiles and well-established fundraising operations.

“We’re going to make sure that the promise of America is available to everyone,’’ Castro said before a cheering crowd on Saturday in his home town of San Antonio, Texas.

Castro took the first step toward a run in December when he formed an exploratory committee that allowed him to raise and spend a limited amount of money to test whether he can generate support for an official bid.

Democrats are piling on for the opportunity to take on President Donald Trump, whose job approval rating halfway through his four-year term hovers around 42 percent, according to a Real Clear Politics survey of recent polls.

Younger Generation

At 44, Castro will be one of the youngest candidates, a generation younger than potential competitors like Senators Bernie Sanders, 77, and Elizabeth Warren, 69, as well as former Vice President Joe Biden, 76. Yet with so many better known contenders considering the race, including fellow Texan Beto O’Rourke, Castro will have to work to stand out. He only barely registers in polls, and sometimes isn’t included as an option at all.

Warren, of Massachusetts, formed an exploratory committee at the end of last year and has campaigned in Iowa, which in February 2020 will hold the first contest in the months-long slog of caucuses and primaries leading up to the nomination. Former Maryland Representative John Delaney also has formally entered the race.

Among the other possible candidates expected to make decisions soon are Senators Cory Booker of New Jersey and Kamala Harris of California. Hawaii Representative Tulsi Gabbard said on Friday she plans to run and will soon make a formal announcement.

American Dream

Castro is leaning on his life story — from the grandson of a Mexican immigrant to Harvard Law School and beyond — to sell an optimistic take on the need to keep the American Dream alive for all.

“Today we’re falling backwards instead of moving forward,” he said. “And the opportunities that made America, America are reaching fewer and fewer people.”

Speaking about his grandmother, Victoria, Castro said: “I’m sure she never could have imagined that just two generations later, one of her grandsons would be serving as a member of the United States Congress and the other would be standing with you here today to say these words: I am a candidate for President of the United States of America.”

Castro is a fluent Spanish speaker, a possible advantage in states with large Hispanic populations such as Florida and Arizona. He addressed Saturday’s crowed in English and Spanish, and a mariachi band performed during the event. Castro attended public schools in San Antonio before going to Stanford University and then Harvard.

Running a City

He’ll also be able to tout his experience in the federal government and in running a major city. He was mayor of his hometown of San Antonio from 2009 until 2014, when he joined Obama’s cabinet as secretary of Housing and Urban Development.

Castro spoke little of Trump on Saturday, but referred to the current debate over the president’s call for a wall on the U.S.-Mexican border that has created a partial federal government shutdown now into its fourth week.

“We have to have border security, but there’s a smart and humane way to do is,” he said. “And there is no way in hell that caging babies is the right way to do it.”

If he wins, he’d be the first identical twin elected president. His brother, Joaquin, is a member of the House from Texas. Joaquin Castro will be chairman of his twin’s campaign. Castro’s first stop as a presidential candidate will be in Puerto Rico on Sunday.

Michael Ahrens, a spokesman for the Republican National Committee, said in an emailed statement that Castro “has made history by becoming one of the biggest lightweights to ever run for president. He was a weak mayor who couldn’t even handle being HUD secretary.”