* U.S. indexes off highs, European shares edge lower
* Vote on U.S. healthcare reform bill set for 3:30 p.m. (1930 GMT)
* Failure might shift agenda straight to tax reform
* Gold prices gain as dollar edges lower (Updates to close of European markets)
By Sam Forgione
NEW YORK, March 24 (Reuters) - U.S. shares pared gains and European shares slipped on Friday as investors were on tenterhooks awaiting the outcome of a vote in Washington on healthcare legislation reform, seen as pivotal for U.S. President Donald Trump's pro-growth agenda.
The benchmark U.S. S&P 500 and the tech-heavy Nasdaq Composite edged off their highs of the day, while the Dow was little changed amid uncertainty that Trump and the Republican leaders who crafted the healthcare bill had enough support to pass it, meaning they now risk defeat in their first attempt at major legislation and a key campaign pledge.
Trump warned House Republican lawmakers that he will leave Obamacare in place and move on to tax reform if they do not get behind new healthcare legislation in a vote on Friday. The White House said the vote was scheduled for 3:30 p.m. EDT (1930 GMT).
The back-and-forth over the bill has led to some of the choppiest trading Wall Street has seen since Trump’s election in November. Investors had grown worried that a failure of the legislation would damage prospects for Trump’s pro-growth agenda items – tax reform and stimulus – which led earlier this week to the biggest daily drop U.S. stocks have seen since the election.
Some analysts and investors, however, say failure of the bill would be a catalyst to bring forward action on tax reform in particular.
"If this goes on the back burner and they start addressing corporate tax rates or infrastructure, that would be a positive for the market," said Bucky Hellwig, senior vice president at BB&T Wealth Management in Birmingham, Alabama.
MSCI's all-country world equity index was last up 0.98 point, or 0.22 percent, at 448.46.
The Dow Jones Industrial Average was last down 6.27 points, or 0.03 percent, at 20,650.31. The S&P 500 was up 3.73 points, or 0.16 percent, at 2,349.69. The Nasdaq Composite was up 26.11 points, or 0.45 percent, at 5,843.80.
Europe's broad FTSEurofirst 300 index closed down 0.16 percent at 1,484.54.
The U.S. dollar index, which measures the greenback against a basket of six major rivals, was last down 0.12 percent at 99.639, leaving it near a roughly seven-week low of 99.547 touched on Wednesday.
That allowed safe-haven gold prices to edge higher. Spot gold prices, which hit a more than three-week high on Thursday of $1,253.12 an ounce, were up 0.22 percent at $1,247.51 an ounce.
U.S. Treasuries prices rose and yields dipped ahead of the vote, with benchmark 10-year yields last at 2.405 percent, from 2.418 percent late Thursday.
“This is being seen as a good litmus test of the rest of Trump‘s agenda,” said Gennadiy Goldberg, an interest rate strategist at TD Securities in New York.
Oil prices edged higher but remained on track for weekly losses of about 2 percent as concerns persisted over an excess of crude.
Brent crude was last up 7 cents at $50.63 a barrel. U.S. crude was up 15 cents at $47.85. (Additional reporting by Patrick Graham and Libby George in London, Tanya Agrawal in Bengaluru and Karen Brettell and Caroline Valetkevitch In New York; Editing by Nick Zieminski and James Dalgleish)