Sens. Elizabeth Warren (D-MA) and Michael Bennet (D-CO) are putting pressure on big tech firms to explain their motives for donating to President-elect Donald Trump’s inauguration fund. In letters to Amazon, Apple, Google, Meta, Microsoft, OpenAI, and Uber, the lawmakers express concerns about the companies making contributions to “avoid scrutiny, limit regulation, and buy favor.”

Over the past several weeks, Google, Microsoft, Apple CEO Tim Cook, Meta, Amazon, and OpenAI CEO Sam Altman all donated $1 million apiece to Trump’s inauguration, while Uber and its CEO, Dara Khosrowshahi, each contributed $1 million. Many of these tech execs have already met with Trump, and Meta CEO Mark Zuckerberg is even hosting an inauguration party for the incoming president, according to The New York Times.