Investors’ concerns over the prospects of a U.S. tax overhaul dragged down stocks after the Dow industrials had posted seven consecutive sessions of gains.

The blue-chip index was down as much as 253 points around midday Thursday as investors parsed developments in a tax overhaul they have been anticipating since the election of President Donald Trump. But major indexes pared their declines in the second half of the trading day.

The Senate plan to push through a different tax proposal than what the House released last week has caused some investors to question Republicans’ ability to get a bill through to the White House.

Investors said Thursday’s losses accelerated after reports that the Senate’s proposal would delay the corporate-tax-rate cut until 2019.

“Some investors have been buying in anticipation of stocks being able to report that they are earning more by paying lower taxes,” said Kim Forrest, a senior portfolio manager with Fort Pitt Capital Group. “This would’ve been an easy win for corporations and investors.”