US President Donald Trump waves as he boards Air Force One for a trip to California, his first as president

San Diego (AFP) - Fresh off a cabinet reshuffle, President Donald Trump headed for Democratic stronghold California on Tuesday to inspect prototypes of the controversial border wall with Mexico that was the centerpiece of his White House campaign.

“I’ll see you at the wall, I’ll see you at the wall,” an upbeat Trump told reporters after explaining his decision to replace Rex Tillerson as secretary of state with CIA chief Mike Pompeo.

Trump’s visit to the “Golden State,” the most populous in the country, is the Republican’s first since his election and comes more than a year after he became president.

California has been at the forefront of resistance to Trump’s anti-immigration agenda and at odds with his stance on a number of other issues, from gun control to marijuana and the environment.

Trump will fly into Miramar air base in southern California before going to San Diego to see prototypes of the wall he wants to build on the southern border.

Prototypes of the border wall with Mexico are seen above the current border fence from the Mexican town of Tijuana

Eight full-scale models made of concrete and steel have been erected side-by-side at Otay Mesa along the border with Tijuana, Mexico.

Colored beige, brown and gray and up to 30-feet (nine meters) tall, the prototypes tower over the existing graffiti-covered border fence.

Six US companies built the mockups and they are being assessed for their anti-breaching capabilities.

Each prototype cost more than $300,000 and, according to some estimates, the complete wall could carry a $20 billion pricetag.

Despite Trump’s campaign promise to “Build the wall!” Congress has yet to approve the necessary funding for the project amid skepticism and Democratic opposition.

- ‘Nothing but hate’ -

Trump addresses reporters before heading to California

The eight hulking prototypes can be seen from across the border in Tijuana, where residents are not overly impressed with the real estate tycoon who launched his presidential campaign calling Mexicans “criminals” and “rapists.”

Ahead of the visit, a few dozen people gathered for a pro-Trump rally on the US side of the border, near the prototypes, while a similar number of the president’s detractors came to the San Ysidro border post.

“This is an environmental catastrophe, on top of a misallocation of government resources that could be used for health care or social services,” Cody Petterson, president of the San Diego County Democrats for Environmental Action, said of the wall.

Student Rebecca Montes, 22, told AFP she had turned up to support undocumented friends and relatives.

“I’m of 100 percent Mexican descent. It’s always been stressful for them but with the Trump cabinet being so vocal (against immigrants) the pressure has been enforced upon them,” she told AFP.

A woman in glasses, hair scraped into a bun, described herself as a “proud Latina” born and raised in San Diego.

“My parents were deported when I was 15. Did I cry? Yes. How many more tears do we need? Do we need another trail of tears?” she said.

“This president speaks nothing but hate.”

Demonstrators draped themselves in US flags and waved placards emblazoned with slogans such as “Love Trumps hate,” “Resist unstable idiot,” “Immigrants they get the job done” and “No hate in the Golden State.”

- ‘You can get over it’ -

On the Mexican side, deportees, immigration activists and Trump opponents prepared to protest in front of shipping containers lined up in a row to shield the visiting president from view.

Mexican federal police set up a security cordon around the area, just in front of the existing border fence – a corrugated metal barrier covered in graffiti, with the eight prototypes towering just behind it.

Police blocked off two neighborhoods that jut up against the border, Las Aguilas and Rancho Escondido. Only residents with official ID were allowed inside.

Pointing to one of the structures, Eladio Sanchez, 30, admitted that it might slow him down, but “you can get over it anyway.”

“It’s just a little more complicated,” said Sanchez, adding he has sneaked into the United States on several occasions.

The border with Mexico stretches nearly 2,000 miles (3,200 kilometers) and about a third of it already has some type of barrier or wall.

Trump’s insistence that Mexico pay for the wall has soured relations and Mexican President Enrique Pena Nieto recently canceled plans to visit Washington amid continuing disagreement.

There is also plenty of opposition to Trump’s wall – and other policies – on the US side of the border in this heavily Democratic state where Hillary Clinton won more than 61 percent of the vote.

Attorney General Jeff Sessions has accused the state of deliberately obstructing enforcement of federal law by offering sanctuary to undocumented immigrants.

Governor Jerry Brown said the Trump administration “is basically going to war” against his state after the Justice Department sued to block its sanctuary laws.

Trump is expected to wrap up his visit with an evening of fundraising in Beverly Hills to raise money for his 2020 re-election campaign.