Zandi said the payroll tax cut expiration, other tax hikes and the $85 billion in across-the-board spending cuts are "taking an bite out of the economy."
"They are all starting to kick in now and have an effect on the economy."
The report comes two days ahead of the government's monthly figures for public and private job creation as well as the unemployment rate.
By all indications, job creation is throttling back to 125,000 a month, which won't be strong enough to reduce the job rate.
Construction added 15,000 jobs but manufacturing reported 10,000 jobs losses last month, the first decline in three months and the largest since September.
A separate manufacturing report is due out Wednesday morning, which should provide a sharper view of what is happening in the sector.
Small businesses still led the way in jobs growth with 50,000 in April.
The services sector added 113,000 jobs last month, which was the weakest pace in seven months.