NEW YORK (March 27): U.S. equity index futures dropped at the open on Sunday, after President Donald Trump's stunning political setback on Friday when Republican leaders pulled legislation to overhaul the U.S. healthcare system.

S&P 500 e-mini futures were down about 0.5 percent, shortly after electronic trading resumed on Sunday evening.

Markets were unnerved last week by Trump's inability to get enough support for legislation to overhaul the U.S. healthcare system, a major 2016 election campaign promise of the president and his allies.

Trump suffered a stunning political setback on Friday in a Congress controlled by his own party when Republican leaders pulled the bill, just before the markets closed.

Stocks ended slightly lower on Friday as they pared losses in late-afternoon trading. For the week, the S&P 500 fell 1.4 percent, its worst weekly decline of the year.

Investors had worried that the difficulties with the health bill could delay other legislation such as tax reform. Trump said he would now turn his attention to getting "big tax cuts" through Congress.

Speaking on "Fox News Sunday," White House chief of staff Rance Priebus said the administration was open to working with moderate Democrats and Republicans to pass other aspects of Trump's agenda, such as revamping the tax code.