From left, Sen. Tom Harkin, D-Iowa, Sen. Sherrod Brown, D-Ohio, and Sen. Jack Reed, D-R.I., are backed up by students during a news conference on Capitol Hill in Washington, Tuesday, May 8, 2012, as the Senate moved toward a showdown on a Democratic proposal to keep federally subsidized loan interest rates from doubling for millions of college students. (AP Photo/J. Scott Applewhite) Sens. Tom Harkin (D-Iowa), left, and Sherrod Brown (D-Ohio) (J. Scott Applewhite/AP)

As some Republicans in Congress push to scale back and otherwise reform entitlement programs, a pair of liberal senators are pushing to expand one of the programs — Social Security.

Sens. Sherrod Brown (D-Ohio) and Tom Harkin (D-Iowa) are spearheading the effort, which they say would increase benefits for all Social Security beneficiaries by about $70 per month, change the cost-of-living calculation for benefits, and increase the amount that the wealthiest Americans pay into the program.

Social Security taxes are currently capped at the first $113,700 of someone's income. Brown and Harkin say the tax increase would help sustain the program, which is solvent but is on track for significant deficits in future decades.