NEW YORK, May 16 (Xinhua) -- The U.S. central bank would respond with a more aggressive monetary easing than markets currently anticipate when facing an upcoming economic downturn, a U.S. economist said on Thursday.

The Federal Reserve (Fed) would cut benchmark fund rates by 0.25 percentage points by the end of 2019 and further slash the rates by 0.5 percentage points by the end of 2020, Michael Pearce, senior economist with Capital Economics, said at the research firm's annual conference.

The United States would see economic growth below 2 percent in the coming quarters amid lagged impacts of past monetary tightening, Capital Economics predicted.

The annualized growth of U.S. gross domestic product (GDP) would fall to 1.7 percent in the second quarter of 2019 in contrast to 3.2 percent in the first quarter, said Pearce.

The quarterly annualized U.S. GDP growth is expected to further drop to around 1 percent in the third and fourth quarter of 2019 before seeing improvement in 2020, according to Capital Economics.

Pearce said the odds of a recession in U.S. economy in the next 12 months are one in three and that the next recession is likely to be fairly mild and short-lived.

The Fed has over 70 percent of probability of cutting the benchmark interest rates by 0.25 percentage points or more by the year end, according to online FedWatch Tool with CME Group.

At its regular policy meeting which ended on May 1, the Fed decided to maintain the target of Federal fund rates unchanged at 2.25 percent to 2.5 percent and indicated that no more hikes will be coming this year.

The Fed kicked off a round of monetary tightening in December 2015 with the aim of having a neutral monetary policy and saving space for easing in case of economic downturn.