(Reuters) - HCA Healthcare Inc’s profit missed estimates for the second straight quarter, hurt by higher expenses and weaker-than-expected patient volumes, and the hospital operator cut its full-year earnings forecast, sending its shares down 4 percent.

Hospital operators’ stocks have been volatile as Republicans march on with their attempt to dismantle the Affordable Care Act, popularly known as Obamacare, raising concerns that a healthcare overhaul will curtail the benefits hospitals have gained from expanded insurance coverage.

President Donald Trump made a last-ditch plea on Monday to U.S. Senate Republicans to “do the right thing” and fulfill campaign promises to repeal and replace Obamacare. The Senate will vote on Tuesday on whether to open debate on an overhaul of the law.

Results have been challenged by a softer managed care and exchange volume growth, with the London market affected by a strong dollar and lower admissions, HCA noted on a conference call.

KeyBanc Capital Markets analysts view the softer volume growth as slightly negative for other hospital companies.

Smaller rivals Community Health Systems Inc and Tenet Healthcare Corp were down about 8 percent, while Lifepoint Health Inc fell 2 percent.

Same-facility managed care and exchange admissions were 27.7 percent of total domestic admissions, down from 28.3 percent a year earlier, HCA said.

Its equivalent admissions, which include patients who stay in the hospital overnight and those who are treated on an outpatient basis, rose 1.3 percent in the quarter.

Mizuho Securities USA analyst Sheryl Skolnick said it was now clear that HCA needed external growth to augment slowing organic growth.

“And that doesn’t make us comfortable given pressures on same-store utilization rates.”

HCA has been scooping up hospitals from rivals including Community Health and Tenet Healthcare as it looks to bulk up.

Net income attributable was largely flat at $657 million, or $1.75 per share, in the second quarter ended June 30, lower than analysts’ estimate of $1.80, according to Thomson Reuters I/B/E/S.

HCA, which operates 172 hospitals and 119 freestanding surgery centers, reported a 4 percent growth in revenue at $10.73 billion, but it was below analysts’ estimate of $10.85 billion.

HCA now expects earnings per share for the year in the range of $7.00 to $7.30, down from $7.20 to $7.60 it previously forecast.

Despite the weaker quarter, Piper Jaffray analysts said it was a good opportunity to acquire HCA shares given their investment into higher acuity and faster growing services.