After President Obama's campaign team spent two weeks trying to put presumptive Republican presidential nominee Mitt Romney on the defensive over his private-sector investment record, Republicans are hitting back today with new ads questioning the president's public-sector investment record.

In a post-Memorial Day ad blitz, the Romney camp and a conservative super PAC both released new Web ads that point to Solyndra as a symbol of a failed effort to pick winners and losers with taxpayer funds.

The new ads come as Romney made a symbolic visit to the northwestern Colorado town of Craig -- which depends heavily on mining and one of the nation's largest coal-fired power plants -- to blast Obama's stimulus spending and a regulatory mind-set that the former Massachusetts governor says is contributing to high unemployment.

The Romney visit and new ads come just days after the second anniversary of Obama's trip to Solyndra, the now-bankrupt California solar energy company that received more than $500 million in federal funding. It was during that trip that Obama famously declared that "the true engine of economic growth will always be companies like Solyndra."

"You've heard of Solyndra; they took $535 million in taxpayer loan guarantees and went bankrupt. But that's not even half the story," an announcer says in Romney's new Web video.

The ad then highlights other companies that received stimulus money -- including First Solar Inc., a Tempe, Ariz.-based company involved in three projects that together have received more than $3 billion in Energy Department loan guarantees. The company saw nearly $450 million in losses in the first quarter of 2012 and has had to fire 30 percent of its staff and reduce production.

Combined with the Solyndra failure, the issues at First Solar and several other companies that received millions in government funding have cast a cloud over DOE's entire stimulus-backed loan program. And as they did with Solyndra, Republicans have worked to highlight the ties between the companies that received stimulus funds and major Obama backers who also invest in those companies.

"Obama is giving taxpayer money to big donors and then watching them lose it. Good for them, bad for us," Romney's ad states.

Just as that ad was dropped this morning, the Karl Rove-backed conservative group American Crossroads launched its own Web video blasting Obama for playing "Wall Street games" with taxpayer money.

The group, which has spent $1 million dollars on Solyndra-related television ads since last fall, coined the term "public equity investing" in its ad today.

"If President Obama wants to attack private equity, that's fine -- but let's open up his failed record as a public equity investor, where jobs were lost and taxpayers were left holding the bag," American Crossroads spokesman Jonathan Collegio said in an email today announcing the new ad.

The Obama campaign today sought to focus on Romney's efforts to hold a fundraiser tonight with billionaire Donald Trump in Las Vegas. In its own Web video today, the Obama campaign called Trump one of the "voices of extremism" in the Republican Party because he continues to question the president's place of birth. The Obama video calls on Romney to stand up to Trump as Sen. John McCain (R-Ariz.) famously stood up to defend Obama's citizenship during the 2008 campaign.

Promoting energy jobs

During his speech before a cheering crowd in Craig, Romney poked fun at the president's "all of the above" energy message and commitment to clean-energy jobs, saying, "Have you seen those around here anywhere?"

The Republican presidential candidate added about Obama: "He's made it harder to get coal out of the ground; he's made it harder to get natural gas out of the ground; he's made it harder to get oil out of the ground."

Craig hotel owners Frank and Kerrie Moe urged Romney to visit their community. The two were featured in a video earlier this year highlighting the negative effects of federal and state energy policies.

"New regulations came into play; more restrictions came into play. All those revenues that were coming from energy-based companies, energy-based exploration and development, were fleeing the state," Kerrie Moe says in the video, titled "The Perfect Storm Over Craig, Colorado."

She tearfully added that she and her husband had to lay off people for the first time in 15 years.

"If those coal units shut down, that coal mine shuts down, that town shuts down," American Energy Alliance head Thomas Pyle says in the video.

AEA produced the five-minute clip along with Americans for Prosperity and the Institute for Energy Research under the banner Energy for America.

While he mentioned coal, at one point pointing out a "coal equals jobs" sign in the crowd, Romney stuck to his basic talking points, criticizing the president on stimulus spending and high unemployment.

"We are glad that Governor Romney is acknowledging the important role that coal plays in our economy, and we urge President Obama to reconsider these over-reaching EPA rules," American Coalition for Clean Coal Electricity Senior Vice President Evan Tracey said in a statement.

During a speech in Iowa last week, Obama touted his commitment to boosting clean-energy production. His backers say fossil fuel industries are exaggerating the impact of regulations meant to protect the environment and public health.

"Now is not the time to cut these investments just to keep giving billions in tax giveaways to oil companies. They've never been more profitable," Obama said. "Now is the time to double down on biofuels and solar and wind, clean energy that's never been more promising for our economy and our security and for the safety of the planet."