President Barack Obama says Social Security is slowly running out of money but that it can exist well into the future with a slight fix.

The system is funded with a tax on earnings, up to $109,000 a year. Obama says lifting that cap to tax a larger share of income would be one way to extend the system of monthly payments for retirees. It also would be unpopular with some.

Without an adjustment, Obama said Social Security will start to run out of money in about 20 years as more people begin collecting benefits.

Obama spoke Friday at a town-hall meeting in Henderson, Nev., the home state of Senate Majority Leader Harry Reid. Republicans are targeting Reid for defeat in November's midterm elections.