U.S. stocks climbed, with the S&P 500 Index on track to halt its longest losing streak since February, amid shifting speculation on whether Britain will remain in the European Union.

Equities recovered from a 1 percent selloff as both sides suspended campaigning on whether Britain should leave the EU after Labour Party lawmaker Jo Cox was murdered as she met constituents in her electoral district. She was in favor of remaining in the EU, fueling speculation voters will be more likely to choose remain in next week's referendum. Phone companies and utilities rallied, while energy producers were mired in the longest retreat in almost 10 months as crude continued to fall.

"Recent polls have shown Brexit is too close to call, or leaning in the direction of leaving," said Mark Luschini, chief investment strategist at Philadelphia-based Janney Montgomery Scott LLC, which manages $54 billion. "That campaign cooling a bit could provide relief to investors that think further campaigning will help drive votes in the direction of a Brexit. How sticky of a sentiment that will be is yet to be determined."

Traders noted the rebound in equities coincided with a deterioration in chances Britons would elect to leave the EU as tracked by Oddschecker's survey of bookmakers' implied probability. Those odds slipped below 38 after surpassing 44 hours earlier. Others said a rebound in markets was unsurprising given how fast stocks fell at the open, with the S&P 500 going as low as 2,050.37, roughly where it began a 1.4 percent rally on May 24.

Investors were also shrugging off anxiety over the growth outlook after the Federal Reserve yesterday scaled back its projections for interest-rate increases, indicating the economy remains mixed, while also citing Britain's June 23 referendum on EU membership as a factor in its decision to stand pat. Chair Janet Yellen pointed to more permanent forces that could hold down rates for longer, namely slow productivity growth and aging societies. Officials also now expect a slower pace of hikes in both 2017 and 2018.

The Bank of Japan refrained from expanding monetary stimulus ahead of a domestic election and the U.K.'s June 23 Brexit vote, while the Swiss National Bank and Bank of England also kept rates unchanged.

Equities were on track to end a retreat spurred as investors weighed the potential fallout from the U.K. referendum, with a series of polls indicating more Britons favor leaving the EU. Sentiment has soured from just a week ago, when the S&P 500 rose to within 0.6 percent of a record on optimism that a mix of low rates and moderate economic growth would continue to support higher stock prices. The gauge had rallied as much as 16 percent from a 22-month low in February.

"Central banks have sounded the alarm over a potential Brexit, with chiefs of the Fed, Bank of Japan, Bank of Canada and Swiss National Bank all citing next week's vote as a potential disruption to the global economy. Yellen said yesterday the decision could have consequences for financial markets, and "in turn for the U.S. economic outlook." Traders have cut back their bets on a Fed rate increase, pricing in only a 4 percent chance of a July boost and less than 40 percent odds of one as late as February 2017.

While policy makers still aren't seeing enough momentum in the economy to warrant higher borrowing costs, a report today showed the cost of living in the U.S. excluding food and fuel rose in May, propelled by rising rents. Separately, jobless claims increased more than expected last week, reflecting a jump in California that otherwise masked steady progress in the U.S. labor market. Another gauge showed confidence among homebuilders climbed to a five-month high in June.