In a surprise move on the last day of its term, the US Supreme Court largely upheld the constitutionality of the Patient Protection and Affordable Care Act (PPACA), otherwise known as President Obama’s health care reform package. Although the court struck down the part of the law that would have allowed the government to withhold existing Medicaid funding to states that don’t comply with an expansion of the program, a majority of the court— including Chief Justice John Roberts—ruled that while the individual mandate would not stand under the Constitution’s commerce clause, it was acceptable as part of Congress’s taxation authority.

So for now, Obama’s landmark health care legislation will stand at least until next year. While the court has had its final word on the issue, if Republicans maintain control of the House of Representatives and win both the Senate and the presidency, they can still repeal the PPACA. But if Democrats can at least hold the Senate, they can prevent a repeal bill from ever reaching the president’s desk. And if Obama is reelected he will surely veto any repeal sent his way.

So the electoral “silly season” is sure to be even sillier than usual this year. With most polls currently showing Obama and Republican contender Mitt Romney in a statistical tie, well within the margin of error, expect the rhetoric from both sides to be especially heated over the next few months.

That will produce the kind of uncertainty the market hates, especially when the global economy is already showing signs of weakness. Businesses will attempt to defer any major decisions, while investors will avoid committing serious capital until there’s greater clarity on what their tax situation will look like next year. That likely means a market governed by inertia, with a downside bias.

So our democracy, the very thing that makes America great, is now also one of our economy’s most significant headwinds. Barring another round of the Federal Reserve’s so-called quantitative easing between now and the election, the market is unlikely to make a meaningful move to the upside and could even give back much of its recent gains.