CLEVELAND (Reuters) - Cleveland police on Friday tightened their security plan for the Republican National Convention after the deadly shootings of police officers in Dallas, increasing surveillance and intelligence operations just 10 days before the convention.

Cleveland mounted police look on prior to Republican U.S. presidential candidate Donald Trump speaking at a campaign rally in Cleveland, Ohio, March 12, 2016. REUTERS/Aaron Josefczyk

Other police departments across the country required officers to patrol in pairs rather than alone following the ambush in Dallas, the deadliest day for police in the United States since the Sept. 11, 2001, attacks on New York and Washington.

In Cleveland, the attack raised another potential threat during the July 18-21 convention, when Donald Trump is expected to receive the Republican nomination for president.

The police officers’ labor union, rank-and-file cops and some outside experts had already questioned Cleveland’s preparedness for the convention with the city’s police under federal supervision over use of force.

Ten days before the event, Cleveland was still training police officers for duty at the convention, which is expected to draw 50,000 visitors as well as clamorous protests and crown the most contentious presidential candidate in memory.

Rather than a security team reinforced by the country’s largest police departments as it hoped, the city has cobbled together 3,000 officers, mostly from state agencies, who will use borrowed and rented equipment.

“When the convention was awarded to Cleveland (in 2014), folks weren’t thinking about this.... Yes, there is a generalized worry,” said Matthew Barge, court-appointed monitor for the U.S. Justice Department’s oversight of Cleveland police.

CLEVELAND POLICE CONFIDENT

Ed Tomba, the city’s deputy police chief and head of convention security, had previously told Reuters he was “very, very confident” in the city’s convention plan. He reiterated that confidence in a telephone interview on Friday in response to the Dallas attack.

“We have got to make some changes without a doubt,” Tomba said, mentioning the surveillance of potential threats from street level and farther away.

“We will have plenty of people watching over different locations. We are beefing up the intelligence component, too. They are going to be very, very active,” Tomba said.

Police throughout the United States ordered their officers to work in pairs following the shooting in Dallas, including those in New York, Chicago and St. Louis.

New York officers will “double up” on all assignments and auxiliary police officers who are unarmed except for night sticks will not be used in the field for the next few days, Police Commissioner William Bratton told a news conference.

St. Louis police also will be required to wear ballistic vests when leaving any station for enforcement activities, Chief Sam Dotson said on Twitter.

Tomba said he spent part of Friday morning reassuring out-of-town police departments that their officers on loan to Cleveland will be safe during the convention, telling them in an email that “we cannot pull the plan off without them.”

Cleveland police union President Steve Loomis has been among the most vocal critics, complaining that front-line officers would be undertrained and poorly equipped.

“They are setting up my guys for failure,” Loomis said before the Dallas attack.

Civic leaders have said Cleveland is experiencing a renaissance following decades of decline, and that reputation will be on the line during the convention.

Two separate incidents of fatal police shootings in recent years have brought unwelcome national attention to the city.

In 2012, 13 Cleveland officers fired 137 shots into the car of an unarmed African-American man and his female passenger, killing both. The U.S. Justice Department investigated and imposed special federal oversight known as a consent decree that remains in force.

Then in 2014, four months after the Republicans chose Cleveland for the convention, a white police officer shot dead 12-year-old Tamir Rice, who was black, in a case that became a national focal point for the protest movement Black Lives Matter.

The most recent report from the federal monitor overseeing the Cleveland consent decree portrays a police department where physical infrastructure is strained, with computers and cars “run-down or deficient,” forcing police to pay for repairs out of their own pockets and use their personal vehicles for police work.

Loomis, the union leader, said half of Cleveland police officers have yet to receive convention training.

That number is “probably close,” Tomba said on Thursday.

Upon getting the convention, Cleveland asked 200 police departments to send officers, including those from big cities which generally have the best anti-terrorist schooling.

Many big cities turned Cleveland down, saying they were unable to spare officers, Tomba said.

But Cleveland has exceeded its goal by bringing in 3,000 reinforcements who will receive training at home plus a short course upon arriving, Tomba said.