Last week, I reported that the Congressional Budget Office was updating some of its cost estimates of the national health care law as part of its regular budget review process. But today, 37 Senators led by freshman Sen. Ron Johnson, R-Wis., sent a letter to CBO director Doug Elmendorf asking for a re-estimate of the entire law in light of new information.

Several factors could make the health care law significantly more costly than advertised at the time of passage in March 2010. For instance, the law was crafted in a way to delay enactment of the major spending provisions until 2014, to make the legislation appear cheaper under the CBO’s 10-year budget window (then 2010 to 2019).  Now, the budget window has moved up to 2022, meaning it takes into account an extra three years of full enactment.