In the Wall Street Journal, former Bush CEA chairman Edward Lazear writes:

Since 2008, the ratio of federal spending-to-GDP has risen by about 14%. From 2008 to 2009 we saw the greatest annual increase in spending in the last 30 years. In the name of stimulating job growth, the share of federal spending is now 24% of the economy, up from 21% in the last year of the Bush administration.

Current OMB director Peter Orszag counters:

On January 7, 2009, the Congressional Budget Office issued its Economic and Budget Outlook for Fiscal Years 2009-2019.  In that document, CBO projected that government spending would rise from 20.9 percent of GDP in fiscal year 2008 to 24.9 percent of GDP in fiscal year 2009.  (Just for the record, that CBO projection was issued 2 weeks before the current Administration took office.)

This week, CBO issued its updated Economic and Budget Outlook for Fiscal Years 2010-2020.  That document shows that government spending in fiscal year 2009 turned out to be 24.7 percent—roughly the same as what CBO had initially projected.  (The mix of spending was slightly different from what CBO had projected, with somewhat lower mandatory spending and somewhat higher discretionary spending as a share of the economy.

For the record, as a professional blogger, I consider having government officials writing blog posts refuting Wall Street Journal op-eds to be a dangerous encroachment by Big Government upon a vital function of the private sector.