President Barack Obama has often said he's proud of what his administration has done to reduce the federal deficit, particularly after the immediate challenges of the Great Recession subsided.

During the 2012 campaign, he offered some specifics about what he hoped to do during his second term.

"I'll make sure the government does its part by cutting away spending we don't need," Obama said. "We've already cut a trillion dollars of spending we didn't need and we can do more. I want to do another trillion, trillion and a half of cuts."

There's little question that Obama presided over significant spending cuts during his second term. The cuts were thanks in large part to a widely-complained-about framework of across-the-board spending cuts known as sequestration.

Still, getting to the $1 trillion to $1.5 trillion benchmark he laid out in his promise requires some generous math.

"Like anything else in budgeting, it's all about the baseline," said Steve Ellis, vice president of Taxpayers for Common Sense. "It's a cut relative to what?"

The most obvious way to judge how much spending went down on Obama's watch is to start with how much spending was expected in 2012, when he made the promise, and then compare that to the amount of spending that actually materialized. To determine how much spending was expected in 2012, we used 2012 projections from the Congressional Budget Office, a widely trusted nonpartisan source for budget numbers.

Over the final five years of Obama's presidency -- 2012 through 2016 -- projected spending minus actual spending totaled a cumulative $427 billion. That's a significant amount of savings, but it's less than half the lowest benchmark Obama offered in his 2012 campaign promise.

It's possible to reach Obama's target if you go beyond his presidency proper. Adding current projections for spending over the first four years of his successor's term produces a cumulative $1.534 trillion in savings between 2012 and 2020.

One can argue that Obama should take credit for these additional dollars saved by steering spending on a steady course, but it's important to note that the figure for 2012 to 2020 is heavily reliant on projections made using today's assumptions about future events. (Not only are there always unexpected contingencies, but Donald Trump will almost certainly have different spending priorities and patterns than Obama did.)

Here's a summary table of CBO's projected spending minus actual spending:

Meanwhile, there's another way to tally up "savings" -- taking what the administration had proposed spending in each of the past five fiscal years, then subtracting the actual amount the government ended up spending.

Using this method, the savings between 2013 and 2017 add up to a bit over $1 trillion. That reaches the lower end of Obama's target range. Here are the details:

But this method has shortcomings, too. Regardless of which parties happen to control the White House and Congress, the president's spending proposal is inevitably considered a starting point in negotiations -- a wish list more than an ending point. For this reason, it doesn't seem appropriate to give Obama credit for achieving savings from what amounts to a high-ball starting proposal.

Ultimately, Obama deserves credit for hundreds of billions of dollars in savings when measured using the most cautious methodologies. But he only can only reach the $1 trillion to $1.5 trillion he laid out in his 2012 promise by using more permissive standards that are of questionable value. We rate this promise a Compromise.