Barring unexpected bad economic news in the next several days, the Federal Reserve will finish its bond-buying program at the end of this month. In all, the program has pumped $3.5 trillion into the economy since 2008, helping to revive financial markets and stabilize the economy.

Now comes the hard part.

In its effort to wean the economy off of extraordinary monetary support, the Fed’s next task is to decide when to raise interest rates from their prolonged ultralow levels.

Technically, the decision is straightforward. It is appropriate to raise rates when the economy shows signs of overheating, as measured by inflation in wages and prices. Currently, there are no such signs. Wages have long stagnated, even for college-educated workers. As for prices, the Fed’s preferred annual inflation measure was recently 1.5 percent, well below its 2 percent target.

Politically, however, the decision is fraught. The Fed is not supposed to be swayed by elected officials or special interests. But bond holders — a powerful political constituency that includes financial firms, investment funds and wealthy individuals — generally want the Fed to raise rates sooner rather than later, and they have ample opportunity to dominate public discourse. Their aim is to pre-emptively attack inflation, which diminishes the value of their bonds.