The growing congressional scrutiny of pharmaceutical giant Mylan over the high cost of EpiPens could prove awkward for Sen. Joe Manchin.

The West Virginia Democrat’s daughter, Heather Bresch, is chief executive of the company, which appears to have hiked the price of the epinephrine auto-injector by 400 percent since 2007. The device, which is used to treat severe allergic reactions, now costs more than $600 per dose.

This price increase has become a public relations disaster for Mylan and at least four of Manchin’s Senate colleagues are either pressing the company to reduce the cost of EpiPens, asking it to explain the price increase or requesting federal regulators to investigate the matter. Manchin is not a member of the Senate Judiciary Committee, which has shown the most interest in probing Mylan’s pricing practices, and so far the senator is not discussing the issue.

“Right now we don’t have any comment,” Manchin spokesman Jon Kott said in an email Tuesday.

Senate Judiciary Committee Chairman Charles E. Grassley (R-Iowa) on Monday sent a letter to Bresch requesting information about how Mylan determined the price of EpiPens and whether the company provides assistance to patients to help with the cost. Grassley said he has heard concerns about the high cost of EpiPens from many constituents, including a man in Iowa who recently had to pay more than $500 to refill his daughter’s EpiPen prescription. The letter asks the company to respond by Sept. 6. Congress is out of session until after Labor Day.

Separately, Sen. Amy Klobuchar (D-Minn.) is calling on the Senate Judiciary Committee and the Federal Trade Commission to investigate the price increases immediately, and Sen. Richard Blumenthal (D-Conn.) sent a letter to Mylan demanding that it lower the price of EpiPens.

On Tuesday, Sen. Mark R. Warner (D-Va.) sent Bresch a similar letter seeking an explanation for the price hike.

“I am deeply concerned about this significant price increase for a product that has been on the market for more than three decades, and by Mylan’s failure to publicly explain the recent cost increase,” Warner wrote.

In a statement released Monday, Mylan did not directly address pricing strategy, but said it is proud of the programs it has implemented to support access to epinephrine, including a patient assistance program and a program that provides free EpiPens to U.S. schools.

Mylan employees and the company’s PAC contributed a total of $60,750 to Manchin between 2011 and 2016, according to the Center for Responsive Politics.

This isn’t the first time a business decision by Mylan has proved awkward for Manchin. In 2014, through a deal with Abbott Laboratories, the company was able to incorporate in the Netherlands — a move that let it lower its tax bill through what is known as an inversion.

The practice of U.S. companies moving their headquarters abroad to lower their taxes has popped up as a political issue in recent years. The Obama administration has advanced rules intended to curtail the practice but Congress has not acted on the issue.

President Obama has called inversions an “unpatriotic tax loophole.”

In a July 2014 interview with National Journal, Manchin was asked whether the type of tax move engineered by his daughter was the right thing to do for companies.

Manchin didn’t directly answer the question but said he would support a law ending the practice.

“I think basically inversion should be absolutely repealed,” he told National Journal.