Representatives of Thousand Oaks-based Amgen Inc. and Pfizer Inc. attended a lobbying group meeting with President Donald Trump on Thursday, according to a Reuters report.

The PhRMA lobbying group met with Trump to voice opposition to a bipartisan U.S. Senate bill aiming to lower prescription drug prices. PhRMA argued that the legislation would impose harmful price controls in Medicare Part D, the program for self-administered prescription drugs.

The bill would cut prices on prescription drugs sold to Medicare and other government programs, the report said, by forcing companies to pay rebates to Medicare if prices go above the rate of inflation.

The Trump administration also aims to put a cap on out-of-pocket costs for drugs under Medicare Part D and include updates to Medicare Part B, which covers physician-administered drugs.

The legislation is backed by the White House; lowering drug prices was a main campaign point for Trump in 2016, and is still an important topic leading into the November 2020 presidential election.

The bill moved to the Senate floor on Thursday after being reviewed by the Senate Finance Committee. Reuters was not able to confirm what other drug makers were at the meeting.

Shares of Amgen (AMGN) closed Thursday down $1.66, or nearly 1 percent, to $174.11 on the Nasdaq.