CAMP DAVID, Maryland (Reuters) - President George W. Bush on Saturday demanded Congress approve a free trade agreement with South Korea this year, calling it a White House priority.

“I assured him the Korea free trade agreement is a priority for this administration,” Bush said after a meeting with new South Korean President Lee Myung-bak at the U.S. presidential retreat.

Congress “must reject protectionism, must not turn its back on a friend and ally like Korea, must approve the free trade agreement with Korea this year,” Bush said.

But he will likely face a tough fight with Democrats who control the U.S. Congress because many have concerns about whether the deal will ensure that American automakers have fair access to the Korean market.

The U.S. International Trade Commission estimates the Korea-U.S. free trade agreement, or KORUS, could raise U.S. exports by an additional $10 billion to $12 billion, making it the biggest U.S. trade deal in about 15 years.

But Democrats, including presidential hopefuls Sens. Hillary Clinton and Barack Obama, have complained the deal does not adequately address access to the Korean auto market.

A spokesman for U.S. House of Representatives Speaker Nancy Pelosi, a California Democrat, said on Friday that issue should be resolved before Congress considers the deal. The White House said it was too early for such pronouncements.

U.S. trade officials have said the pact does much to open South Korea’s market to additional U.S. auto exports and gave no indication they were willing to re-negotiate.

Pelosi already put on ice another free trade pact negotiated by the Bush administration, one reached with Colombia, amid concerns about the health of the U.S. economy. An agreement with Panama also is pending.