The Fed is expected to extend the "Operation Twist" stimulus programme, which expires this month, under which it buys longer-term securities funded by the sale of short-term ones, with the goal of suppressing long-term borrowing costs.
Some speculate that central bank could also expand the "Operation Twist" programme by extending the average maturity of its portfolio.
The Fed is due to release a statement at 1630 GMT.
Fears about Europe's debt crisis abated slightly on Tuesday, as Spanish 10-year yields fell after a short-term debt sale showed that country was still able to access international markets to fund its debt.
Further tests will come on Thursday, when Spain is due to sell up to 2 billion euros of two-, three- and five-year bonds.
"We have to see what the Fed does, but we also have to see how Spain's debt sales later this week proceed. If Spanish yields rise again, we could see Treasury yields head down," said a fixed-income fund manager at a Japanese asset management firm.
Investors' improved risk appetite pressured safe-haven German Bunds, and the gap between 10-year Bunds and higher-yielding US Treasuries narrowed to 9 bps from 17 bps late on Monday.
The yield on 10-year notes edged down to 1.61 percent from 1.62 percent in late US trade, but were well above 1.56 percent in Tokyo on Tuesday.
The yields on 30-year bonds stood at 2.72 percent, down slightly from 2.73 percent in late US trade, but up from 2.65 percent in Tokyo trade on Tuesday.
On Tuesday, the Fed bought $1.72 billion in debt due between 2022 and 2031 as part of the "Operation Twist" programme.