Arizona Sen. Mark Kelly said Tuesday that Vice President Kamala Harris only had a short amount of time to think before stating that she supported decriminalizing illegal border crossings in 2019. 

"You're talking about a primary in 2019 where somebody throws their hand up and you’ve got like a half a second to think about it," Kelly said, defending Harris for her previous statements in favor of decriminalizing border crossings. 

Harris has previously supported decriminalizing illegal crossings and ending private detention. 

BORDER SENATOR AND FORMER HARRIS VP SHORT-LISTER CLAIMS 'NO EVIDENCE' ILLEGAL IMMIGRANTS VOTE

Sen. Mark Kelly on CNN

Arizona Sen. Mark Kelly said Tuesday that Vice President Harris only had a short amount of time to think before stating that she supported decriminalizing illegal border crossings in 2019.  (CNN)

"Today, what really matters is who is standing with the Border Patrol agents, and that’s Kamala Harris," Kelly said. "Who has killed probably the best opportunity we had to do bipartisan legislation — this is the way this should be done, and the person who killed it was Donald Trump."

"[Trump] should not be leading on this issue in the state of Arizona," Kelly said when confronted with polling data that indicates that Trump is considered more trustworthy than Harris on the issue of border security. 

"Kamala Harris has stood for border security," Kelly said. "She wants to get something done on this issue. She's led on this issue." 

Kelly, a key political figure in the border and swing state, said that Trump made a mistake by not supporting the Emergency National Security Supplemental Appropriations Act. 

Harris has spoken out multiple times in favor of decriminalizing illegal immigration and even shutting down Immigration and Customs Enforcement (ICE).

"An undocumented immigrant is not a criminal," Harris said in 2017.

'FOR ELECTION PURPOSES': CRITICS BALK AT HARRIS' CLAIM SHE WILL 'ENFORCE OUR LAWS' AT SOUTHERN BORDER

Harris at Georgia campaign event

Harris had previously promised as a presidential candidate in 2019 to shut down immigration detention centers on "day one." (Win McNamee/Getty Images)

Harris had previously promised as a presidential candidate in 2019 to shut down immigration detention centers on "day one." In other remarks, she had also talked about ICE potentially starting "from scratch."

"I think there’s no question that we’ve got to critically re-examine ICE and its role and the way that it is being administered and the work it is doing," Harris told MSNBC in 2018. "And we need to probably think about starting from scratch."

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The Harris campaign did not immediately respond to a request for comment from Fox News Digital

Fox News' Julia Johnson, Chad Pergram and Tyler Olson contributed to this report.