On the day before he formally accepts the Republican presidential nomination, Mitt Romney slammed President Obama in a speech here Wednesday for military budget cuts that he said would devastate the country’s already beleaguered economy.

Romney said the automatic defense cuts known as “sequestration” that are scheduled to take effect Jan. 1 would result in as many as 1.5 million lost jobs and a significant decline in the overall economy, as well as impair long-stretched veterans’ programs. If he is elected, Romney told the national convention of the American Legion, his administration would not impose such cuts.

“A year ago, President Obama told your national convention that, ‘We cannot, we must not, we will not balance the budget on the backs of our veterans,’ ” Romney told the veterans organization. “I thought I’d finally agreed with him on something. But now he’s on the verge of breaking that promise. The Obama administration is set to cut defense spending by nearly a trillion dollars. My administration will not.”

Romney made a day trip to Indianapolis to address the American Legion, an opportunity he called “a privilege not to be missed.” But minutes after finishing the speech, Romney headed to the airport for a flight back to Tampa. He is scheduled to be in the convention city in time to watch the prime-time speeches, including by his vice presidential running mate, Rep. Paul Ryan (Wis.).

In his address here, Romney made it clear that he sees the economy as the driving issue in the race against Obama. But he said the first job of the government is to keep the American people safe.

“When a country is hurting at home, the biggest political debates are understandably about domestic issues — how to get small business growing again, how to get jobless Americans back to work, how to show people who feel trapped in this stagnant economy that the hard times won’t last forever because a better future is about to dawn,” Romney said.

“But you and I know that our debates can change suddenly with a ringing phone in the dead of the night, or a grim-faced reporter in the middle of the day, or a plume of smoke on a clear, blue morning,” he continued.

The Obama campaign was quick to respond to Romney’s comments.

“Throughout this campaign, Mitt Romney has offered a lot of reckless bluster and vague platitudes but zero specific national security policies — and that continued at the American Legion today,” Lis Smith, spokeswoman for Obama’s campaign, said in a statement. “If Mitt Romney were truly serious about helping veterans, he’d tell Congressman Ryan and his Republican allies in Congress to work with the President to achieve a balanced deficit reduction plan that includes asking millionaires and billionaires to pay their fair share while investing in veterans and the middle class — as the President’s plan does.”

Romney also tore into Obama over a backlog of disability claims and long waits for mental-health treatments at the Veterans Administration. “Beyond the president’s failure to deliver an economic recovery, and beyond what I see as reckless defense cuts, are the reproachable failures at the VA itself,” he said.

Romney also cited a request by the Obama administration to increase fees for Tricare, the veterans’ health insurance program.

“I will not ask our wartime military to shoulder sacrifices while the rest of government grows,” Romney said. “I’ll not ask our service members, active or retired, to pay more for their health care to free up room for Obamacare.”