Federal Reserve Chairwoman Janet Yellen and other central bank officials are likely to end their large-scale bond-buying program this week, while simultaneously promising lower interest rates for longer to stimulate the economy.

As members of the Federal Reserve System converge in Washington on Tuesday for a two-day meeting that will culminate with an official monetary policy statement, they are set to cut the last $15 billion of monthly bond purchases to zero, ending the stimulus program that began in late 2012 and has seen the Fed’s balance sheet expand from $2.8 to $4.5 trillion.