SINGAPORE (July 24): Boris Johnson has won the race to be the next British prime minister. But with the incoming prime minister having just 100 days to negotiate a new Brexit deal with the European Union before the end of October, Johnson now faces a race against time.

Even as potential horrors loom with the Halloween deadline, all eyes will now be on how Johnson behaves his first few weeks in office.

Observers say Brexit negotiations could hinge on whether Johnson sticks to his hitherto hardline stance on Brexit or adopts a softer approach.

See: Boris Johnson wins race to be next British prime minister

“It is not easy to predict which way this will go,” says Quentin Fitzsimmons, fixed income portfolio manager and resident Brexit specialist at asset management firm T. Rowe Price. “In either case, I believe it is almost certain that Johnson will not be able to secure an improved Brexit deal from the EU.”

The way Fitzsimmons explains it, Johnson’s comments during the leadership campaign have raised expectations of the UK leaving the EU without a deal on October 31, which would lead to widespread jitters in the markets.

“At the same time, there is a growing sense that UK economic fundamentals—along with those of most of the rest of the world—are deteriorating, increasing expectations of a Bank of England rate cut by the end of 2019. Combined, these developments have sent investors piling into safe haven assets, causing UK sovereign bonds to rally sharply in recent weeks,” he adds.

Already, British businesses deeply concerned about no-deal have urged Johnson to avoid crashing out of the EU.

“This idea of leave-what-may on October 31st is hugely worrying businesses because of the effect on investment and jobs,’’ Carolyn Fairbairn, director-general of the Confederation of British Industry, is reported as saying in an interview with Bloomberg.

MPs opposed to a nodeal Brexit have already begun trying to block Prime Minister Johnson from taking the UK out of the EU on October 31.

Labour leader Jeremy Corbyn told the BBC that the main opposition party will call for a no-confidence vote in Boris Johnson’s government at the “appropriate time”.

“If the UK leaves without a deal on October 31 and there is clear immediate disruption to the supply of goods, the resulting panic could push yields sharply lower,” Fitzsimmons says. “However, if there is less disruption than anticipated, yields may rise sharply.”