PHILADELPHIA (Reuters) - U.S. Vice President Joe Biden warned House of Representative Democrats on Friday that Republicans are trying to take credit for a strengthening economy and urged his party to tout the stimulus, auto bailouts and health care reforms engineered by the Obama administration.

Biden, speaking at a Democratic policy retreat in Philadelphia, said that unless Democrats explain how these policies helped the economy, Republicans will persuade Americans in an "orchestrated effort" that their election victories last November sparked a stronger wave of growth and hiring.

"This is our story, the Democratic party's story," Biden said. "It's about how government policy can and did change America. And people are attempting to steal that story."

New Senate Majority Leader Mitch McConnell earlier this month said a recent uptick in the economy "appears to coincide with the biggest political change of the Obama administration's long tenure in Washington: the expectation of a new Republican Congress."

Biden said that if Democrats let Republicans take credit for recovery, they will have less credibility to push their future policies, such as new spending on education and infrastructure.

"The point here is that Democrats have to stand up," he said. "You've got to embrace what we did. Explain it, be proud of it, stand up for it, defend it. We can't let the Republican party rewrite history."

Obama on Monday is releasing his fiscal 2016 budget plan, which will seek to boost both domestic and military spending by easing automatic budget constraints known as "sequestration."

(Reporting by David Lawder; Editing by Leslie Adler)