I am very impressed with what Liljenquist was able to do as a freshman Senator. He headed up the reforms to Utah's pension system which removed billions of dollars of risk from the taxpayers.
Liljenquist also was charged with reforming Utah's Medicaid system. The reforms passed the legislature unanimously and will save the state over $700 million over the first 7 years alone.
Here are a few articles about the resignation:
Dan Liljenquist resigns en route to expected challenge of Orrin Hatch - Salt Lake Tribune
Liljenquist resigns from Utah Senate, may challenge Hatch - Deseret News
Sen. Dan Liljenquist resigns - Fox 13
Sen. Liljenquist resigns, expected to challenge Hatch - ABC4
Liljenquist resigns from state Senate - Standard-Examiner