President Obama took steps to preserve the office allowances given to former presidents Friday, by vetoing a measure that would have capped those expenses at $200,000 a year.

The veto comes less than six months before Obama will become a former president himself. But Obama suggested in a message to Congress that his veto was more about the "unintended consequences" the bill would have on his predecessors.

At issue: The expense allowances that former presidents get to travel and maintain an office. Obama said that by capping those allowances at $200,000, some current former presidents would have to lay off staff, cancel leases or even return office furniture.

Under current law, the General Services Administration must provide "suitable office space, appropriately furnished and equipped." The total cost of maintaining and staffing those offices currently ranges from $430,000 for former President Jimmy Carter to $1.1 million for former President George W. Bush, according to a report by the Congressional Research Service.

The Presidential Allowance Modernization Act of 2016 would have removed the GSA's role in providing office space, instead giving a flat $200,000 allowance.

"Unfortunately, this bill as written would immediately terminate salaries and all benefits to staffers carrying out the official duties of former Presidents – leaving no time or mechanism for them to transition to another payroll," White House Press Secretary Josh Earnest said in a statement. And he said the cuts could even impact Secret Service protection for former presidents.

Earnest said Obama agrees on the need to reform presidential pensions, and would sign a bill if Congress makes "technical fixes to resolve these issues."

Obama's veto was something of a surprise. The White House had not issued a veto threat on the bill, and he waited a full 10 days before sending it back late on a Friday when Congress wasn't in session.

House leaders couldn't immediately be reached for comment on whether they would seek to override the veto. The bill had passed both the House and the Senate by voice votes.

The veto was Obama's 11th of his presidency. None of his vetoes have been overridden.

The bill, sponsored by Rep. Jason Chaffetz, R-Utah, would also have capped presidential pensions at $200,000 a year, with a cost-of-living increase, and phased out pensions for presidents making $400,000 a year in outside income.

The White House said it consulted with every living former president about the bill before Obama vetoed it.