I cringed yesterday as I watched Senators Obama and Clinton duke it out in Ohio over who is more anti-NAFTA. The whole thing left me wondering if the candidates realize they may be jeopardizing their ability to win California in the general election. To be sure, the stridently anti-NAFTA rhetoric plays well in certain sectors, including some rust bucket states. But it's poison here in Silicon Valley and, if it continues, the anti-trade rhetoric could help push Silicon Valley's generally moderate money and power base toward the likely GOP nominee, Senator John McCain, come November. It's that serious.

Don't get me wrong. I am sure NAFTA can and should be improved. It would certainly be fair for the Democratic presidential candidates to call for improving NAFTA. No problem there. What's alarming, though, and potentially damaging, is all the heated anti-trade rhetoric emerging from the two remaining Democratic presidential candidates as they angle for support from John Edwards voters in these last few crucial do or die primaries. Unfortunately, this latest stage of the competition has left both candidates sounding like protectionists (note to presidential candidates: protectionism has very few fans in places such as Silicon Valley).

As they compete for support in Ohio, Obama and Clinton risk losing the support they'll need to put California in the win column in the general election. Clinton's proposal to impose a moratorium on trade agreements, for example, throws the anti-NAFTAs some red meat at the cost, if implemented, of increasing instability in critical world markets that are vital to the economic health of Silicon Valley. At the same time, Obama's repeated strong assurances that he never, ever, ever supported NAFTA creates the impression that the Senator from Illinois, who has a very thin economic policy resume, may not even support the basic idea of free trade. It also raises the question of whether there was, or is, any version of NAFTA that could gain his support. After all, even the most ardent NAFTA critics usually can envision some circumstances under which they would permit the residents of poor nations to sell stuff to the most prosperous economy in the world.

Let's be clear about this. Companies in Silicon Valley need continued access to global markets to succeed. It's a life or death issue for them. What's more, the leaders of these companies could play a decisive role in determining whether California's electoral votes go to the Democratic nominee, be it Obama or Clinton, or to the GOP's John McCain. These influential, wealthy -- and mostly progressive -- business leaders want a president who champions the development of global markets. They want a president who understands what those growing international markets make possible, including higher environmental, labor and human rights standards over time and the economic integration that enhances global cooperation and, ultimately, the prospects for peace. They also want a president who talks honestly about the way the global economy works, someone unafraid to describe the perils inherent in retreating from those markets, as well as the difficulty of using external pressure to impose environmental or labor standards on trading partners and the need to develop new ways to encourage progress in those areas.

On trade issues, however, Senators Clinton and Obama are beginning to sound a lot like Ross Perot. If this keeps up, industry leaders here in Silicon Valley may soon gravitate to John McCain.