Story highlights The National Republican Senatorial Committee held a postmortem call Thursday

The Executive Director said that Democrats shied away from economic issues

The focus on single issues was using a 'tactic as a strategy,' Republicans said

Republicans gained at least 7 seats in the U.S. Senate in Tuesday's midterms

The strategist in charge of electing a Republican Senate majority thanked Democrats on Thursday for keeping President Barack Obama on the sidelines and building their campaigns around women's issues instead of making an economic argument.

Rob Collins, the executive director of the National Republican Senatorial Committee, told reporters in a postmortem session that Democrats "sidelined their best messenger" by running from Obama.

"They were so focused on independents that they forgot they had a base," Collins said of Democratic campaigns. "They left their base behind. They became Republican-lite."

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The "war on women" message that permeated so many Democratic campaigns up and down the ballot "was a mistake," Collins said — it used "a tactic as a strategy." He praised Republican candidates for being "proactive and having something to say."

"I can't remember a Democrat who spent any kind of money in a significant way talking about the economy," he said. "If I had a choice between talking about the number one issue we saw in every single poll, and talking about a single issue, I would be talking about the number one issue."

Not all Democratic campaigns ran single-issue campaigns.

A number of Democrats, especially those in the party's progressive and labor wings of the party, have highlighted Tuesday winners like Al Franken in Minnesota, Gary Peters in Michigan and Jeanne Shaheen in New Hampshire as candidates who talked about women's issues but also weaved the debate into a larger economic theme.

But even those campaigns were careful to avoid being seen as too close to the president.

Collins and NRSC communications director Brad Dayspring agreed that Obama was a political lightning rod for Democrats — especially late in the campaign.

But they said they were baffled that their opponents didn't use him to rally the base throughout the year and make an argument about the economic successes of the Obama administration -- particularly in the purple states of Colorado, Iowa and North Carolina.

"If you are running to Mark Udall's campaign, there is an argument to be made that unemployment was higher when he took office," Dayspring said. "There is an argument that gas prices were higher when he took office. But they never made it. They stuck to a flawed strategy that talked about birth control and abortion through the election. That was something we never understood."