"This balanced budget aims to make government more efficient, more effective and more accountable. It will go a long way toward getting our fiscal house in order," Majority Leader Mitch McConnell, R-Ky., declared on the Senate floor ahead of debate.
Sidelined Democrats were left protesting that the budget used shady accounting to arrive at its savings while slashing safety net programs for the poor.
"It really is a budget that is insensitive and unaware of the reality of life for working families, and that is sad," said Sen. Dick Durbin, D-Ill.
Passage in the Senate was expected late Thursday or in the wee hours Friday morning, following votes on numerous amendments offered from both sides on topics as disparate as Iran sanctions, water rights, Common Core education standards, paid sick leave, community college and discrimination against pregnant workers. More than 400 amendments had been filed, some aimed at creating tough calls for the Republicans eyeing presidential runs or defending their Senate seats in swing states. Only a fraction of those will come to final consideration but the so-called Vote-a-rama will last into the night.
The budgets themselves are nonbinding and do not require a presidential signature. Instead, once the House and Senate agree on a common plan, lawmakers will have to draft legislation to carry out the program that Republicans have vowed to follow in the wake of campaign victories last fall that gave them control of Congress.
Read More5 things to know about Congress' budget debate
Passage by each chamber, something that has happened rarely in recent years, would be a significant accomplishment as Republicans try to make good on promises of responsible governance. Those pledges have looked remote at some points in recent months as the GOP veered perilously close to a partial shutdown of the Homeland Security Department and encountered roadblocks on other bills.
Both plans squeezed trillions by undoing so-called Obamacare and cutting Medicaid and other programs, but there were differences. House Republicans would convert Medicare into a voucher-like program, while Senate Republicans, eyeing the 2016 campaign in which they must defend their newly won majority, omitted such an approach.
Both blueprints envisioned an overhaul of the tax code, details to be determined later.
Red ink was projected to give way to a small surplus in 2024 in the House plan, and one year later under the Senate's scenario, though it took tricky accounting to get there, including counting the tax revenue from Obamacare even while eliminating the law.
Both the House and Senate versions matched the defense spending number of $612 billion from Obama's budget, though only after committee-level maneuvering and reliance on overseas operations accounts that don't have to be offset. Still, some defense hawks in the Senate were calling for more.
The prospect of sending Obama legislation to repeal the health care law contributed to the unusual degree of unity among House conservatives. Without a budget in place, they noted, the repeal measure would not have special protection against a Senate filibuster—and would not reach the White House.