CNN
In an interview with CNN on Sunday, the former Republican presidential nominee said he was concerned that if Ryan takes on the job as speaker, it may spoil the congressman's chances for potential future White House run.
"We need Paul in two spots at once and, you know, there haven't been a lot of people that have gone on from speaker to the White House, so I'd hate to lose him as a potential contender down the road for the White House," Romney told "State of the Union" host Jake Tapper.
"Whether it's now for the speakership or whether instead we see him hold on and ultimately become potentially a candidate for president, I don't know. It's his decision, but I'm just glad to know him and to know we have him in our quiver."
The House Republican caucus has been rocked by turmoil since House Speaker John Boehner (R-Ohio) announced late last month that he'd resign at the end of October.
House Majority Leader Kevin McCarthy (R-California), the presumptive choice to succeed Boehner, failed to gain traction with the ultra-conservative members of the House who make up the Freedom Caucus. He unexpectedly pulled out of the race after it became apparent he did not have the necessary Republican support.
Ryan has been floated as a top choice for the role, as his wonky supply-side tax reform plans have impressed conservatives and moderates within the Republican Party alike. Many high-profile establishment figures - including Boehner and McCarthy - have pressed Ryan to run as a party unifier.
But the Wisconsin congressman has indicated repeatedly that he is not interested in the job, and he has opted to forgo leadership positions within the party in the past in order to work on crafting policy as chairman of the powerful House Ways and Means Committee.
Ryan has plenty of reasons to be reluctant about making a bid for the job. Beyond the possibility of tainting a future presidential bid, Ryan has cited his distaste for the constant fundraising that comes with the post. He has also lamented the time it would take away from his young children.
And it's not even clear he could win if he does decide to run. Many in the House Freedom Caucus say that while they like Ryan, they still support Rep. Daniel Webster (R-West Virginia) because of Ryan's past positions on the 2008 financial bailout and immigration reform, for example.