(CNN) -- With $100 million in federal taxpayer funds, the U.S. Secret Service has transformed the two cities playing host to the national political conventions into high-tech fortresses.
But there are still questions about whether the cities are prepared to handle the tens of thousands of protesters who are expected to flood into each city.
This week's Democratic National Convention in Denver, Colorado, and the Republican convention in Minneapolis-St. Paul, Minnesota, which begins September 1, have been designated "national special security events," which means the Secret Service is responsible for planning and implementing a security scheme for each city.
"We've been preparing for 15 months and we feel very confident," said Darrin Blackford, Secret Service spokesman. Explore the Secret Service's security plans »
According to the Department of Homeland Security, which oversees the Secret Service, 24-hour operations centers have been set up in each city to monitor the conventions and surrounding areas.
At the Denver joint operations center, the Secret Service will be able to communicate with at least 62 federal, state and local agencies involved in the security plan, ranging from the Department of Homeland Security to the local power utility.
"We need to have the highest level of security at these venues, but we try very hard and go to great length to make sure that these venues are as successful as possible," said Eric Zahren, a spokesman for the Secret Service. "We don't plan on shutting down the city. We want the city to do business and thrive throughout the event."
The Secret Service is calling on a number of federal agencies to help with specific security tasks.
The Federal Protective Service is providing explosive-sniffing dogs, uniformed officers and undercover agents as well as mobile command vehicles. The FBI, armed with a new system that allows instant communication between field offices, will also be at both convention sites in force to monitor and react to any potential terror threats.
The Transportation Security Administration, Customs and Border Protection, the Federal Emergency Management Agency and Immigration and Customs Enforcement will provide assistance as well.
The military also is helping. The North American Aerospace Defense Command is prepared to provide air cover and medical assistance, while the Coast Guard will cover the Mississippi River when the Republicans meet in Minneapolis-St. Paul. The Minnesota National Guard also said it will have 1,000 troops standing by.
But the primary responsibility for street-level security falls to the local police agencies. Each city received $50 million in federal grant money to pay for additional security measures. iReport.com: Riot police block protestors in Denver
The St. Paul Police Department estimated it would require $34 million to bring in and pay 3,500 extra officers. The rest of the money goes for training and new equipment.
"Local taxpayers will not be responsible for any security costs of the Republican National Convention coming to town," said St. Paul Mayor Chris Coleman, adding that the federal cash will benefit the city "well into the future."
But is it enough?
Denver authorities estimate between 20,000 and 50,000 people will be in the city during the Democratic convention, but say they are not sure what to expect.
St. Paul officials have planned for about 25,000 protesters, but the protest groups themselves are hoping for double that number.
In both cities, protesters have been granted permits for marches and the right to yell at convention attendees from designated "demonstration zones," which protest groups have derided as "freedom cages," because they are surrounded by concrete and wire fences.
The American Civil Liberties Union of Colorado and other groups filed lawsuits saying the protest routes and demonstration zones were too far from the Pepsi Center in downtown Denver for convention goers to see and hear them, but a federal judge refused to force the Secret Service to reveal documents about its plans, The Associated Press reported.
Denver-area police have a plan in case the protests turn unruly. The Denver Sheriff's Department has built temporary cells in a warehouse 2˝ miles from downtown that can hold up to 400 people. Watch a tour of the temporary jail »
Demonstrators have derided the temporary jail, which consists of 18 cells constructed from wire mesh, as "Gitmo on the Platte," a reference to the military prison holding terrorism suspects in Guantanamo Bay, Cuba.
"This is America. We have a system in place, so why aren't we using it? Why are we using warehouses?" asked Jordan Hill of the Alliance for Real Democracy.
In St. Paul, the demonstration zones are across the street from the Xcel Center, the site of the Republican convention, but while the space is larger and closer than the protest pen set up in Denver, civil liberties groups remain concerned the preparations are inadequate.
Charles Samuelson, executive director of the ACLU of Minnesota, said the situation could get dangerous if the number of protesters reaches 50,000, the number the advocacy groups estimate will attend.
"I'm concerned that there will be a stampede," he said. "I'm not concerned that the protesters will be violent, but that the police will have to use tactics to get the protesters to move that could lead to a stampede."
CNN's Joe Johns contributed to this report.