Most of the biggest donations in the first half of 2019 have gone to Republicans, who control the Senate and tend to be more reluctant to restrict drugmakers. (Photo: Shutterstock)

In the heat of the most ferocious battle over drug prices in years, pharmaceutical companies are showering U.S. senators with campaign cash as sweeping legislation heads toward the floor.

In the first six months of this year alone, political action committees run by employees of drug companies and their trade groups have given the 30 senators expected to run for reelection nearly $845,000, the latest update to Kaiser Health News' "Pharma Cash to Congress" database shows. That hefty sum stands out with Election Day more than 14 months away.

Lowering drug prices is one of the rare causes that has united Democrats and Republicans, and at least one proposal that would change the way the industry does business could get a vote in Congress this year. One of the most promising and aggressive updates would cap drug prices under Medicare so they do not outpace inflation.