Sen. Tom HarkinTom HarkinThe Hill's 12:30 Report Distance education: Tumultuous today and yesterday Grassley challenger no stranger to defying odds MORE (D-Iowa) is keeping up his iron will in resistance to joining Twitter. Or at least so he said on Monday.

Harkin, appearing on MSNBC, was asked about Sen. Charles Grassley's (R-Iowa) tweets over the weekend that were very critical of President Obama on healthcare reform.

Harkin didn't respond to Grassley's tweets and noted that he has not given way to the seemingly insurmountable social pressures to join Twitter.

"By the way," Harkin said, "have not succumbed to that yet."

Come on, senator. You know you want to...