Marco RubioMarco Antonio RubioHillicon Valley: YouTube to restore Trump's account | House-passed election bill takes aim at foreign interference | Senators introduce legislation to create international tech partnerships Senators introduce bill creating technology partnerships to compete with China DeSantis's rising GOP profile fuels 2024 talk MORE regrets his personal attacks against his GOP competitor for the White House Donald TrumpDonald TrumpTrump State Department appointee arrested in connection with Capitol riot Intelligence community investigating links between lawmakers, Capitol rioters Michelle Obama slams 'partisan actions' to 'curtail access to ballot box' MORE, he told MSNBC Wednesday. 

"In terms of things that have to do with personal stuff, yeah, at the end of the day it's not something I'm entirely proud of," Rubio told the network in a town hall on Wednesday night. 
 
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"My kids were embarrassed by it, and if I had to do it again I wouldn't." 

Rubio had previously shied away from direct confrontation with Trump, but he burst out of the gate in the last debate before Super Tuesday by emptying the opposition research file against Trump.
 
The next morning, he bashed the billionaire as a "con artist" on television and days later poked fun at Trump's hands for being small.

"You know what they say about men with small hands?" Rubio said at a Feb. 26 rally. "You can’t trust them.” 

Despite the more aggressive tack, the Florida senator hasn't gained traction in the GOP nomination fight, falling hundreds of delegates behind Trump and Ted CruzRafael (Ted) Edward CruzCrenshaw pours cold water on 2024 White House bid: 'Something will emerge' Garland's AG nomination delayed by GOP roadblocks The Hill's 12:30 Report: Washington on high alert as QAnon theory marks March 4 MORE. His campaign has pinned all of its hopes on next week's Florida primary. 
 
At the same time,he told host Chuck Todd, "he needed to be stood up to."
 
Rubio also told MSNBC that he wouldn't be anyone's running mate -- including Trump's -- if asked. "I'm running for president."