"There are two things driving the market: Earnings and the news flow out of Washington," said Randy Frederick, vice president of trading and derivatives at the Schwab Center for Financial Research. He noted that earnings may be currently overshadowing the news out of DC.
"The earnings reports have been good thus far," Frederick said. "I see no reason why that wouldn't continue."
Of the S&P 500 companies that have reported thus far, 80 percent have reported better-than-expected earnings, according to Thomson Reuters I/B/E/S.
Amazon rallied 4 percent ahead of their earnings release Thursday after the close.
Stocks also got a boost as interest rates slipped from multiyear highs. The benchmark 10-year Treasury note fell from a more than four-year high to below 3 percent after the European Central Bank kept interest rates unchanged and reaffirmed its stimulative monetary policy stance.
ECB President Mario Draghi said "underlying strength" in the euro zone's economy continued to underpin the bank's confidence despite signs of "moderation" in recent weeks.
He added an "ample degree of monetary stimulus" remained necessary over the coming months.
In economic news, U.S. durable goods orders rose 2.6 percent in March, far more than the expected 1.6 percent gain. Meanwhile, weekly jobless claims totaled 209,000 last week, below a forecast of 230,000.
Investors are also awaiting data on first-quarter GDP, which is set for release Friday at 8:30 a.m. ET.
"We think there's solid economic growth, but we're considerably below consensus," said Randy Anderson, chief economist at Griffin Capital. "The surge in market volatility has led to lower consumer confidence and the economy is near full employment. It's hard to grow GDP when you're basically at full employment."
—CNBC's Sam Meredith contributed to this report.