Senator Clinton’s renewed push to reduce America’s dependency on foreign-held debt is raising questions about whether economic protectionism and further restrictions on free trade will emerge as a prominent theme in the race for the White House.

Yesterday, Mrs. Clinton fired off a letter to the Treasury Secretary, Henry Paulson, and to the chairman of the Federal Reserve Board, Benjamin Bernanke, expressing concern that the Bush administration’s economic policies have made the American economy more vulnerable to decisions made in China, Japan, and other countries.

“What happened over the last 48 to 72 hours should be a real wakeup call for our country,” Mrs. Clinton said during an interview on CNBC in reference to this week’s stock market nosedive. “Obviously, the level of our debt that is now held by central banks and foreign government is a problem. And I don’t want the administration to ignore this wake-up call and just hit the snooze button again.”

Mrs. Clinton said the increase in foreign-owned debt coupled with the loss of manufacturing jobs and the increased dependence on foreign-made products is creating a “slow erosion of our own economic sovereignty.”

Mrs. Clinton’s use of the term “economic sovereignty,” a phrase used by opponents of the North America Free Trade Agreement when President Clinton was pushing it over a decade ago, signaled to some that further trade restrictions could be a big campaign theme in the Democratic field. She has already invoked the issue on the campaign trail, but it’s been largely overshadowed by her vote to authorize the Iraq war and her pledge to push for universal health care. It could be of particular importance in the early caucus state of Iowa, where, in 1988, Rep. Dick Gephardt won after making his opposition to free trade a central campaign theme.

The issue of trade has put Mrs. Clinton in a dilemma. On the one hand, she needs to satisfy labor unions, most of which believe that trade agreements hurt American workers; on the other hand, she must appeal to those who backed her husband when he pushed for NAFTA and ushered China into the World Trade Organization.

Her leading opponents, Senators Edwards and Obama, have said NAFTA needs to be renegotiated, while Rep. Dennis Kucinich has called for its full repeal.

Mrs. Clinton backed NAFTA but voted against the Central American Free Trade Agreement.

“She and her husband should have a talk over the dinner table tonight because I think President Clinton understood those issues pretty well,” the director of the Center for Trade Policy Studies at the Cato Institute, Daniel Griswold, said.

“Economic sovereignty has become a kind of code word for wanting to turn our back on what happens abroad,” he said. “We have everything to gain from importing from the global market place, exporting, and tapping into global capital markets.”

A senior international economist at the Economic Policy Institute, Robert Scott, applauded Mrs. Clinton for bringing attention to the increased costs associated with foreign debt, but he said there is “zero chance that China is going to dump United States treasury bills.”

When asked yesterday on CNBC whether America should limit the amount of foreign-held debt that it issues, Mrs. Clinton said no, but she added that the country needed to get back to fiscal responsibility.

She said, however, that she wants to see the countries we do business with have protections for intellectual property and ensure that they can’t manipulate their currencies.

“I think it’s fair to say, ‘Wait a minute, let’s at least factor it in,'” she said. “There are many, including myself, who are trying to raise — if not a red flag — a yellow one.