The Federal Reserve has to face a big dilemma when it meets this week.

It needs to pretend that the US economy is doing well when economists, even those inside the Fed, aren’t sure it is.

The Fed wants and needs to raise interest rates. And it has already done so five times in the latest cycle. But those quarter-point hikes aren’t enough to get rates back to normal levels — something that needs to be done not only in fairness to savers but also because the Fed must be able to cut rates when the next recession hits.

But in order to keep raising rates, the Fed needs to make a credible case that inflation is about to hit harder than it has been in the official numbers. And for that, it needs the economic numbers to show some life.

I know, inflation really is already bad. But that’s not what the official numbers say.

So the Fed’s policy-making Open Market Committee — in public — will probably talk about things like the overheating labor market (another fantasy) and the fact that the Trump administration’s tax cuts are likely to cause additional economic growth.

And, in the end, the Fed is expected to hike rates by another quarter-point when its meetings end Wednesday.

But the Fed governors who vote on hikes will have this problem: Despite the tax cuts, the economy really isn’t doing much better than it did in the Obama era. In fact, it’s not doing very well at all.

Last week, the Federal Reserve Bank of Atlanta revised downward its projections for growth in the gross national product during the first quarter of 2018. When the quarter ends later this month, the Atlanta Fed thinks the economy will have grown at an annualized rate of just 1.8 percent.

Weeks ago, the Atlanta Fed had thought the economy was on pace for 5.4 percent growth this year.

And just in case you don’t trust the Atlanta Fed’s forecasts, consider that Goldman Sachs lowered its forecast to 1.8 percent annual growth, down from 2 percent, and JPMorgan Chase lowered its to 2 percent, down from 2.5 percent.

Admittedly it might be too early for the tax cuts to have kicked in. And consumer confidence was recently at a multi-decade high. But retail sales — the best indicator that people are spending their tax-break cash — have been lousy. So is the housing market, and stocks are getting some sense knocked back into them.

So just maybe, Trump’s tax reduction isn’t going to work. And maybe the rate hike the Fed is expected to announce on Wednesday will make future economic growth even more disappointing.

That’s the Fed’s problem.

Another problem: The stock market fell sharply on Monday — in large part because of anxiety about what the Fed will do.