The plan put forth by House Budget Committee Chairman Paul Ryan, R-Wis., aims to reduce the top individual income-tax bracket to 25 percent and keep military spending on its current trajectory. (J. Scott Applewhite/AP)

Democrats and Republicans clashed Tuesday over the outlines of Rep. Paul Ryan’s final budget proposal, which would slash $5 trillion of anticipated spending over the next decade and may serve as a key fault line in the November midterm elections.

Ryan (R-Wis.), in his final year as House Budget Committee chairman, opened what will be three days of debate before final passage by hailing his last fiscal blueprint as one that “sets priorities” and makes tough choices on entitlement programs — efforts, he said, that ultimately will lead to balanced federal books.

“Our job here in Congress is to make decisions,” Ryan said.

Democrats have made the document from the GOP’s 2012 vice-presidential nominee a centerpiece of their fall election strategy, arguing that the proposal illustrates how Republicans would behave if they controlled the House and Senate. They have accused the GOP of catering to rich industrialists — such as David and Charles Koch — who are financing an avalanche of negative advertising against Democrats in a few key Senate races.

“Their allies in Congress have produced a budget that shows exactly what the Koch brothers would do if they were in charge: stack the deck for special interests,” aides wrote in a memo from the Democratic Congressional Campaign Committee and the Democratic Senatorial Campaign Committee.

The proposal, expected to pass largely along party lines, will receive a final House vote Thursday.

Democrats have held news conferences on a near-daily basis since Ryan released the budget last week, saying that it sets up a contrast with their narrowly targeted agenda of issues such as college student loan reform and equity pay for female workers.

The Ryan budget is largely a symbolic document because Congress agreed in December to a two-year framework for federal spending, negotiated by Ryan and his Senate Budget Committee counterpart, Sen. Patty Murray (D-Wash.), that has already set in place funding caps for federal agencies in 2015.

“This is political theater,” said Rep. Jared Huffman (D-Calif.), a member the budget panel.

Republicans noted that it marked the fourth straight year that Democrats have tried to make Ryan’s budget proposals a cornerstone of their campaigns, but suggested that this fall voters would focus on the slow economic recovery and lingering questions about the implementation of the Affordable Care Act.

“I think the Ryan budget is a step in the right direction,” Senate Minority Leader Mitch McConnell (R-Ky.) told reporters.

Ryan aims to reduce the top individual income-tax bracket to 25 percent and keep military spending on its current trajectory. About $3 trillion of his savings would come from revamping health care, first by repealing the ACA — but leaving intact taxes and savings from the law — and by altering Medicare into a program in which the elderly would receive premium supports from the federal government but buy insurance on their own.

Another way Ryan’s budget draws savings is by squeezing the federal workforce.

Among other strategies, the Ryan outline aims to shrink the workforce by attrition and require employees to share equally with the government in funding civil service retirement benefits. It would allow agencies to fill only one of three vacancies, with an exception for national security.

The Democratic alternative contains no requirement for employees to pay more toward their retirement benefits, in contrast to the Ryan plan that for most employees would mean an increase in that contribution of about 5.5 percentage points.

Ryan’s plan calls to end a supplemental retirement benefit paid to many federal workers who retire before 62 and also end a student-loan-reimbursement program available to agencies as a recruitment and retention incentive.