Cathey Park of Cambridge, Massachusetts wears a cast for her broken wrist with "I Love Obamacare" written upon it prior to U.S. President Barack Obama's arrival to speak about health insurance at Faneuil Hall in Boston October 30, 2013. REUTERS/Kevin Lamarque

By Amanda Becker

WASHINGTON (Reuters) - Republicans in the U.S. House of Representatives on Friday filed a long-anticipated lawsuit challenging the implementation of President Barack Obama's signature healthcare law over employer-based coverage and payments to insurers, according to court documents.

The lawsuit, filed in a federal court in Washington against the Department of Health and Human Services and the Department of Treasury, targets a decision to delay implementation of the law's employer mandate, which requires employers with more than 50 employees to offer healthcare coverage.

It also challenges a provision of the law that authorizes Treasury payments to health insurance companies.

House Speaker John Boehner, in a statement, said that Obama had bypassed Congress to take "unilateral actions" when implementing the healthcare law, also known as Obamacare.

"If the president can get away with making his own laws, future presidents will have the ability to as well. The House has an obligation to stand up for the Constitution," Boehner said.

Jonathan Turley, the lead counsel for House Republicans on the lawsuit, said in a Friday blog post that the president's actions blurred the lines between branches of government and usurped the ability of Congress to use the "power of purse" during the appropriations process.

The House had passed a resolution in July authorizing the lawsuit.

(Reporting By Amanda Becker, Susan Cornwell and Lawrence Hurley in Washington; Editing by Susan Heavey)