Iowa state Sen. Joni Ernst (R) holds a lead over Rep. Bruce BraleyBruce Lowell BraleyOPINION | Tax reform, not Trump-McConnell feuds, will make 2018 a win for GOP Ten years later, House Dems reunite and look forward Trump: Ernst wanted 'more seasoning' before entertaining VP offer MORE (D-Iowa) in the first nonpartisan poll released since Tuesday's primary.

Ernst leads Braley by 48 percent to 42 percent, according to the live-caller poll conducted by Loras College.

The first-term state senator seems to have benefitted from the attention drawn by her primary, in which outside groups spent heavily to raise her name recognition and her opponents never hit her hard. Fully 70 percent of voters have an opinion of Ernst, more than the 60 percent who have an opinion of Braley.

President Obama, who won Iowa twice by double-digit margins, is underwater there now. His approval rating is at 43 percent, with 54 percent disapproving in the poll.

Republicans are bullish about Ernst's chances. If they can pick off Iowa, the GOP's chances of capturing Senate control get much better.

Most pre-primary polling found Braley with a lead over Ernst, though her name identification has rocketed up in recent weeks due to the primary.

There's also a chance that the poll's timing may have slightly inflated Ernst's numbers, as it came immediately on the heels of her big primary win and amid positive coverage of her campaign but before Braley's first attack ad hit.

The poll of 600 likely voters was conducted on June 4-5 and has a margin of error of plus or minus 4 percent.