Paul Ryan says one of his biggest regrets is the ballooning federal deficit. The evidence shows he has himself to blame.

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• House Speaker Paul Ryan is retiring at the end of the current Congress in January after taking over as speaker in October 2015.
• Ryan said one of his biggest disappointments as speaker was not addressing the growing amount of federal debt.
• As speaker, Ryan oversaw the passage of legislation that will add trillions to the deficit.

In an interview on Thursday, Rep. Paul Ryan said one of the biggest disappointments from his term as House speaker was his inability to address the growing mountain of federal debt.

"On healthcare itself and debt and deficits, it's the one that got away," Ryan said at a Washington Post event.

But as speaker, Ryan helped oversee a rise in spending that is already adding to the deficit. Under his tenure, the amount of outstanding federal debt grew by just over $2 trillion, and the federal deficit expanded from $438 billion in fiscal year 2015 to $779 billion in fiscal year 2018.

And it's projected to get even more pronounced from here. The Congressional Budget Office estimates that the deficit in fiscal year 2019 - which began on October 1 - will be $981 billion. In fiscal year 2020, the deficit will eclipse $1 trillion for the first time since the depths of the financial crisis, the CBO projected.

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While there are plenty of reasons for the growing deficit, recent legislation spearheaded by Ryan has only added to the deficit.

Ryan has had a reputation as policy wonk, and he came into the speakership with goals to address rising spending on entitlement programs. During his tenure as speaker, however, the House did not embark on any significant effort on that front.

According to the Committee for a Responsible Federal Budget, 46% of the fiscal year 2019 deficit will be derived from legislation passed since Trump took office. Of that, $228 billion comes from the GOP tax law - which Ryan cited as one of his major accomplishments - and $188 billion comes from the bipartisan budget agreement.

In 2018, Ryan's last year in Congress, the US will issue $1.3 trillion in new debt, up 146% from the 2017 amount and the most in one calendar year since 2010.

Read more: Trump is suddenly obsessed with the ballooning federal deficit after his signature legislative victories caused it to explode»

The Tac Cuts and Jobs Act is also projected to add to the deficit and debt for years to come. According to the CBO, the TCJA will add around $1.5 trillion to the federal deficit through 2028, even after factoring in any increase in economic growth due to the bill.

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