Bubble, bubble, toil and trouble.

That might as well be the new theme for the U.S. economy. Washington -- the White House, Congress, housing agencies, and the Fed -- have learned nothing from the housing bubble of 2007-08.

So here we go again.  Hillary Clinton and Bernie Sanders keep blaming the last crisis on Wall Street greed and malfeasance - and sure there was plenty of that. The enabler was government through easy money, housing policies that pushed people into low down payment loans many could never repay, and a deluge of debt.

Now look at where we are at in 2015:

The Fed can't get off its zero interest rate policy and the drug of choice for Wall Street is cheap money.

Too big to fail is becoming a self-fulfilling prophecy and the bailouts if these banks fail again will be even pricier than last time.

We've had seven years of zero interest rates and Janet Yellen keeps extending it as some kind of weird Keynesian "stimulus." But it hasn't stimulated growth only a misallocation of financial resources.  Perhaps, hopefully, the Fed can steer clear of the icebergn but the record - think 1999 and 2008 - isn't reassuring.

Next, Fannie May and Freddie Mac are back at it again. These two near-trillion dollar government enterprises are again guaranteeing mortgages with as little as 3 percent downpayments. Hello! These are same kind of subprime mortgages that crashed eight years ago. The housing lobby demands it and Congress complies while taxpayers are back on the hook with the same Fannie and Freddie policies that required $150 billion in bailouts just a few years ago.

Then there is the consolidation of the big banks as Dodd Frank's regulatory costs force mergers. Too big to fail is becoming a self fulfilling prophecy and the bailouts if these banks fail again will be even pricier than last time.

Finally, we have the deluge of government debt.

When the crisis hit in 2008 the national debt stood at a little under $10 trillion.  Now we are at $18 trillion.

States and localities meanwhile continue each year to add to the time bomb of unfunded public pension liabilities. Government is hopelessly overleveraged and now Obama wants to raise the debt ceiling with no spending controls -- a blank check.

One other factor that should make us nervous. In this week's Democratic debate both Hillary Clinton and Bernie Sanders endorsed major tax hikes on investors and investment that could be the final nudge over the cliff.

For their part, Republicans should be warning of the dangers ahead. If they don't, Bush, Wall Street, Republicans, capitalism and tax cuts will be blamed for a meltdown that Washington's blunders again created.