Two weeks after a House subcommittee approved an appropriations bill slashing transportation budgets by more than 30 percent, the counterpart Senate Appropriations subpanel tomorrow will consider its fiscal 2012 spending bill.

The Senate bill, which has not been released yet, is expected to keep levels relatively steady, in contrast to the lower chamber's $55 billion transportation and housing bill that drew the ire of the construction industry for devoting $17 billion to transportation. However, the Senate is still hamstrung by low receipts from the federal gas tax, which will leave their final total well below the $50 billion figure the White House requested.

At a budget hearing in March, subcommittee Chairwoman Patty Murray (D-Wash.) chided the Obama administration for proposing a transportation budget well above current levels without also proposing an alternate funding source. Transportation Secretary Ray LaHood testified frequently in recent months that the administration was asking Congress to come up with a funding source to supplement or replace the existing gas tax.

The House GOP says its budget -- in line with the 30 percent cuts requested by Budget Chairman Paul Ryan (R-Wis.) -- will stay within the means of the gas tax, but state transportation departments and others in the industry say that level is too low to keep up current projects and would leave thousands out of work.

The markup comes a week after Congress approved a six-month extension of the surface transportation program, which was set to expire at the end of the month. Both the House and Senate are working on long-term reauthorization, with the Senate Environment and Public Works Committee considering a two-year bill that would keep spending at current levels, indexed to inflation. That would require an additional $12 billion over two years, which legislators are working to cover without raising the gas tax.

The House appropriations markup saw a good deal of controversy over a measure that would strip funding for Amtrak's state-supported routes, language that is unlikely to pass the Senate. The House bill also attracted questions over reduced funding for transit projects and livability initiatives.

Both bills are likely to change based on authorization work -- if legislators can come up with a new funding source or opt to increase some levels, appropriators may fall in line and adjust their spending bills.

Schedule: The markup is tomorrow at 10:30 a.m. in 138 Dirksen.