Wasn't hard to find:

Sen. Rep. Total % of Congress % of U.S. pop.
Catholic 24 130 154 28.8% 24.5%
Baptist 7 68 75 14.1% 16.3%
Methodist 11 50 61 11.4% 6.8%
Presbyterian 15 37 52 9.7% 2.7%
Episcopalian 10 32 42 7.9% 1.7%
Jewish 11 26 37 6.9% 1.3%
Lutheran 3 18 21 3.9% 4.6%
Latter-day Saints 5 11 16 3.0% 1.9%
United Church of Christ/Congregationalist 6 4 10 1.9% 0.7%
Stone-Campbell 1 6 7 1.3% 1.8%
Christian Scientist 0 5 5 0.9% 0.09%
Eastern Orthodox/Greek Orthodox 2 2 4 0.7% 0.31%
Assemblies of God 0 4 4 0.7% 0.53%
Unitarian 1 2 3 0.6% 0.30%
Christian Reformed 0 2 2 0.4% 0.04%
Seventh-day Adventist 0 2 2 0.4% 0.35%
African Methodist Episcopal (AME) 0 2 2 0.4% 0.58%
Evangelical Free or Evangelical (not further specified) 1 1 2 0.4% 0.5%
Quaker 0 1 1 0.2% 0.10%
Community of Christ (RLDS) 0 1 1 0.2% 0.05%
Foursquare Gospel 1 0 1 0.2% 0.10%
Nazarene 0 1 1 0.2% 0.26%
United Brethren in Christ 0 1 1 0.2% 0.01%
Scientologist 0 1 1 0.2% .019%
Community Church 0 1 1 0.2% N.A.
McLean Bible Church 1 0 1 0.2% 0.005%
"Protestant" (not further specified) 1 20 21 3.9% 2.2%
"Christian" (not further specified) 0 5 5 0.9% 6.8%
unspecified 0 4 4 0.7% 13.2%
TOTAL 100 435 535 100.0%