Nearly 450 former employees of the Environmental Protection Agency sent a letter to the U.S. Senate on Monday denouncing President Donald Trump's pick to lead the agency, Oklahoma Attorney General Scott Pruitt.

The EPA alumni who signed the letter have served under Republican and Democratic administrations, and all raise concerns about Pruitt's fitness for the office. "Mr. Pruitt's record raises serious questions about whose interests he has served to date and whether he agrees with the longstanding tenets of U.S. environmental law," the letter said.

The letter echoes concerns raised in similar efforts by environmentalists, academics and environmental lawyers from Oklahoma about Pruitt's close ties to the fossil fuel and agriculture industries, as well as his record of fighting EPA regulation.

Senate Democrats have also questioned Pruitt's qualifications, sending him hundreds of additional questions after his confirmation hearing about how he would run the EPA and about his past work in Oklahoma. Unsatisfied with Pruitt's responses, they then twice boycotted the committee vote to advance his nomination. In response, Republicans on the Senate Committee on Environment and Public Works last week suspended their voting rules to push through Pruitt's nomination to the full Senate. The date for Pruitt's final confirmation vote has not yet been set.

The letter was sent to Senate majority leader Mitch McConnell (R-Ken.) and the rest of the Senate on Monday. According to McConnell's office, he has not yet released a statement responding to the letter.

"I'm certain the letter does not reflect the opinions of all former EPA employees," John Konkus, a spokesman for the Pruitt confirmation team, said in a statement. "If confirmed by the Senate, Mr. Pruitt looks forward to working with all 15,000 current EPA employees to better serve the American people."

This letter aims to explain "what EPA is required to do, how it works and why law and science matter to its mission," Eric Schaeffer, the letter organizer and a former director of the EPA's office of regulatory enforcement, told InsideClimate News.

"We don't think he's qualified," said Schaeffer, who resigned from his position in 2002 in protest against the George W. Bush administration's policies to weaken agency enforcement efforts. He is now executive director of the Environmental Integrity Project, an advocacy group.

As Oklahoma Attorney General, Pruitt has repeatedly sued the EPA over pollution regulations. He issued more than 50 press releases "celebrating" lawsuits filed against EPA regulations, according to the letter, but he hasn't issued any concerning action he's taken "to enforce environmental laws or actually reduce pollution." Also, former EPA staff accuse him of "going to disturbing lengths to advance the views and interests of business."

The letter cites one example of a critical letter to the EPA about its estimates of methane emissions from natural gas development that was drafted by Devon Energy. Pruitt had failed to disclose the energy company had written the letter.

He has also denied that humans are largely responsible for climate change, which alarms the former EPA officials. "We are most concerned about Mr. Pruitt's reluctance to accept and act on the strong scientific consensus on climate change," they wrote.

Current EPA staff are also concerned about Pruitt's appointment. Dozens of EPA employees joined activists and local politicians at an anti-Pruitt rally in downtown Chicago during their lunch break on Monday. At least three EPA staffers spoke at the rally, talking about their work and defending the agency's role in protecting the environment.