The Federal Reserve has been desperate to buoy the US economy. For a while, they reduced the overnight lending rate, until they could reduce it no more. This is the "free money" that some politicians have been referring to lately.
Yet the "free money" interest rates haven't actually increased lending, because the banks are still reluctant to give it up. So the Fed reached down into its bag of tricks and pulled out something called a quantitative easing, in which it buys mortgage backed securities and treasury bills. There have been 3 of these quantitative easings so far (QE3).
This week, the stock market jumped at the rumor of a further easing, a QE4. It has yet to take shape but it's possible that it could circumvent the obstructionist Congress and give progressives some of what we've been clamoring for.
One way that the QE4 could take shape is more purchasing of mortgage backed securities. This would allow the retail banks to loosen up and lend money for mortgages while minimizing their risk. It's not exactly the mortgage refinancing bill we were hoping to get through, but it's a step in the right direction.
The other way a QE4 could take shape is to encourage municipalities to issue infrastructure development bonds, and then have the fed buy those bonds. This would be a beautiful thing, since it would bypass the reluctant congress to get infrastructure projects financed and rolling, and then take the financial burden away from the municipalities. We were unable to get the Rebuild America Jobs Act passed through the Congress but this would have essentially the same effect.