WASHINGTON, July 18 (Reuters) - Two U.S. Senate Democrats urged President Joe Biden on Monday to declare a climate emergency and use the Defense Production Act to ramp up production of a wide range of renewable energy products and systems including solar panels.

Senators Sheldon Whitehouse and Jeff Merkley, speaking days after an effort to advance climate legislation failed in the Senate, also called on Biden to use the White House "bully pulpit" to draw attention to climate-related crises in the United States.

"It is time for the Biden administration to pivot to a very aggressive climate strategy," Merkley said.

Biden said last week that he would take unspecified steps to reduce climate emissions after Democratic Senator Joe Manchin withdrew support for climate legislation that Democrats had hoped to pass before Congress leaves Washington for its August recess. In the evenly divided Senate, Manchin's support was critical for passage of the legislation, which lacked any Republican backing.

Manchin and Senate Democratic Leader Chuck Schumer had been in talks about $300 billion in tax credits for industries including solar and wind power, carbon capture from power plants, and nuclear power, which generates virtually emissions-free electricity.

Whitehouse said he spoke to the White House about the need to move forward with aggressive executive action, but shared no details. "I've talked to the White House about going on offense and being aggressive and doing all the things that it is within the executive powers to do that have not so far been done," he said.

Whitehouse said the conversation tracked his public call for initiatives ranging from tighter carbon regulations for vehicles and power plants to carbon border tariffs and potential federal litigation against the fossil fuel industry. It was not clear, however, how far the White House could go, after the Supreme Court last month effectively restricted the Environmental Protection Agency from issuing emissions rules involving matters of major "economic and political significance." (Reporting by David Morgan; Editing by Leslie Adler)