Democrats hailed the entry of former gubernatorial candidate Roxanne Conlin into the race against Sen. Charles Grassley (R-Iowa), but she has a ways to go.

Grassley holds a 57-30 lead, according to a new Des Moines Register poll of likely voters. The poll shows Grassley's approval rating, which has declined from the stratosphere into the mid-50s, holding steady at 57 percent.

Conlin, who was her party's 1982 gubernatorial nominee, can still do plenty to improve her name recognition, as 62 percent of voters don't know enough about her to rate her favorability. But generally incumbents in the mid-to-high 50s in head-to-head matchups are thought to be in pretty good shape for reelection.

The poll shows just 39 percent of voters approve and 49 percent disapprove of Grassley for his role in the healthcare debate -- a figure that fits nicely into Democrats' explanation for his decline in approval.

But even with a negative-10 rating on the issue of the day, Grassley isn't showing much in the way of vulnerability at this point.