The ugly odor of protectionism is wafting through Washington, and President Obama should shut it off before it gets stronger.

The huge economic-stimulus bill he signed this week contains two provisions that seem, on the surface, to be saving American jobs. In fact, both clauses could be highly counterproductive, destroying far more jobs than they defend.

The first amendment, dubbed “Buy American,” requires construction projects financed under the bill to use only “iron, steel and manufactured goods ... produced in the United States.” Sounds good, particularly when the unemployment rate is 7.6 percent and headed higher. But what if other countries retaliate by imposing similar restrictions that cut off the flow of American exports?

Robert Zoellick, president of the World Bank, bluntly told The New York Times: “The ‘Buy American’ provision is very dangerous.”

The second clause restricts the ability of financial institutions receiving federal aid to hire foreigners holding H-1B visas, special permits for well-skilled and educated workers. These workers are absolutely essential for innovation and job creation. If we kick them out, other countries with a more enlightened view of the world economy will snap them up.

As economist Vivek Wadhwa of the Harvard Law School wrote recently in BusinessWeek: “We will scare away the world’s best and brightest who have always flocked to our shores. But the next Silicon Valley won’t be located in the U.S. It will likely be in Hyderabad or Shanghai.”