Senate Majority Leader Harry Reid (D-Nev.) warned Democrats on Saturday that they couldn't afford a loss in Iowa's "critical" U.S. Senate race, because it would hand Republicans control of the chamber.

Speaking of Republican candidate state Sen. Joni Ernst on a conference call hosted by the Progressive Change Campaign Committee, Reid said, "She's so far to the right that maybe even a part of the right wouldn't like what she's talking about."

Reid urged progressive activists to make phone calls to Iowa voters on behalf of Rep. Bruce Braley (D-Iowa), whom he described as "a fine man" with "a good record of public service."

"If we win Iowa, we're going to do just fine," he said. "Iowa is critical. There's no other way to say it."

The majority leader, who has taken an active role in boosting Democratic Senate candidates across the country ahead of Tuesday's midterm elections, criticized Ernst for refusing to meet with the editorial boards of several Iowa newspapers.

"She's so out of line with mainstream Iowans, mainstream Americans, that she refuses to appear before editorial boards," Reid said. "She has spent the entire campaign talking about what she did as a young girl, castrating animals. That is not the issue."

Ernst said this week that she wasn't expecting to receive the endorsement of the Des Moines Register even if she sat down with the paper's editorial board as initially scheduled.

"They made it clear in a number of editorials they would not be supporting my candidacy," Ernst told Fox News on Thursday. "It's important for me to be out on the road meeting with voters across Iowa, allowing them to reach out and shake my hand and ask me tough questions. It's better to be on the road than to sit in front of a board that was not going to endorse me."