WASHINGTON - Supporters and opponents of Republican presidential nominee Donald Trump Saturday clashed in the US city of San Diego in California.
Police declared a gathering outside the city's convention centre unlawful and made 35 arrests, as stones and water bottles were thrown.
At the same time, media reports say a constant stream of changes and scuffles are unsettling Trump’s campaign team, including the abrupt dismissal this week of his national political director.
A sense of paranoia is growing among his campaign staff members, including some who have told associates they believe that their Trump Tower offices in New York may be bugged, The New York Times reported, citing three people briefed on the conversations.
Trump was in San Diego near the Mexican border to hold a rally ahead of the 7 June California primary.
He has pledged to build a border wall to keep out illegal immigrants.
Saturday's skirmishes flared as the convention centre emptied following Trump's rally, and supporters and opponents met in the streets, jeering and heckling each other. Dozens of police officers in riot gear had been deployed to separate them.
Some protesters scaled a wall of the centre to throw water bottles at police.
San Diego's population is about one-third Latino and hundreds of thousands of people cross the border with Mexico legally each day.
On Friday, Trump backed out of an offer to debate with Democratic candidate Senator Bernie Sanders, the Democratic presidential candidate.
"As much as I want to debate Bernie Sanders - and it would be an easy payday - I will wait to debate the first place finisher in the Democratic Party, probably Crooked Hillary Clinton, or whoever it may be," the Trump campaign said in a statement.
Sanders told reporters on the campaign trail that he hoped Mr Trump would change his mind."Well Mr Trump, what are you afraid of?" he said, calling the Republican nominee a "bully".
Trump said the Democratic nominating process was "rigged" - and that Mrs Clinton and Democratic National Committee Chairwoman Deborah Wasserman Schultz would not allow Sanders to win the nomination.
In fact, Mrs Clinton has a substantial lead among pledged delegates - those apportioned to candidates based on the results in each state - as well as the party representatives called super delegates. She has received around 2.9m more votes than Sanders during the primary season.
The latest opinion polls suggest Mrs Clinton leads Trump by about four percentage points.
Meanwhile, two months after assurances that the candidate would become “more presidential” and transition to a more unifying phase of his campaign, The New York Times said Trump continues to act as if the primary is still underway. His team has struggled to fill top positions, such as communications director, and Trump has made clear he still sees himself as his own chief adviser.
This week, Trump fired Rick Wiley, his national political director, after Wiley clashed with campaign officials in three states. And while fights among aides are not unusual, the daily leaks of damaging information from his campaign are prompting worry among Republican officials.
“Candidate Trump needs to better understand that he is now the titular head of the G.O.P.,” said Scott W. Reed, senior political strategist for the US Chamber of Commerce. “His words and actions will have an impact on the over 6,000 GOP candidates running for office — from federal races down to the courthouse.”
Asked for comment about his management style, and the current state of his campaign, Trump declined, criticizing the reporters writing this article. “You two wouldn’t know how to write a good story about me if you tried — dream on,” Mr Trump said in an email relayed by his spokeswoman, Hope Hicks.
So far, Trump has shown little inclination to adjust to a political world. His penchant for setting up competition and infusing tension between his subordinates has carried over from his real estate company.