RENO, Nev. -- It's a small buy, just $42,000 of online video, but a spot launched this weekend from the conservative American Crossroads demonstrated how conservatives are trying to widen the divisions of the Democratic primary.

"Hillary's Wall," aimed at Spanish-speaking voters in Nevada, uses well-known but infrequently-replayed clips of a Bush-era Hillary Clinton saying she opposed "illegal immigration" -- a phrase no Democrat now utters -- and voted for a border fence. That slams right into footage of Donald Trump, who has quickly become a figure of fear and derision for Latinos.

Super PAC American Crossroads released this online video, linking Democratic presidential candidate Hillary Clinton to Republican frontrunner Donald Trump. (American Crossroads)

It's the latest example of conservative messaging aimed at the Democratic base, exploiting the growing liberal sentiment that Clinton cannot be trusted and Sen. Bernie Sanders (I-Vt.) can.

"It wasn’t that long ago that Hillary Clinton sounded just like Donald Trump on the subject of illegal immigrants,” said Ian Prior, American Crossroads's spokesman, in a cheeky missive to reporters.

This web buy is a fraction of what the Ending Spending Action Fund poured into Iowa -- $800,000 on an ad that branded Sanders as "too liberal" in all the ways Democratic voters liked. Less was spent on an American Crossroads spot that warned Iowa Democrats of Clinton's "Wall Street" donations. The Clinton campaign's response then was the same as now: They doth protest too much.

"Republicans continue to spend money attacking Hillary Clinton because she is the candidate they do not want to face," said Clinton spokesman Brian Fallon. "She was the first candidate to challenge Trump after his announcement last year when he made derogatory comments about Mexican immigrants."

Still, in this ad and in the "Wall Street" spot, Crossroads is trying to amplify a critique coming from increasingly restless progressives. In Nevada, the first Democratic contest where Latino voters represent a sizable bloc, the Sanders campaign is trying to make voters aware of the stances Clinton took before she was a 2016 candidate.

"Let's go back to 1996," Rep. Raul Grijalva (D-Ariz.), one of the very few Sanders endorsers in Congress, said in a town hall with Latino Sanders volunteers this weekend. "I know that Bernie's opponent was not the president of the United States. He husband was. But in 1996, the law was passed with the Newt Gingrich and others, the Illegal Immigration Reform and Immigrant Responsibility Act. That act introduced to us the first hard steps toward criminalization of immigrants for a civil offense. Being an unauthorized entry, all of a sudden family reunification was almost impossible. Bernie says that law needs to be fundamentally changed."

There were some gasps and shaking heads at that information, and some laughter at what Grijalva said next. "She wasn't president -- certainly no guilt by association! -- but she should take a position on that," he said. "Bernie voted against the fence. Then-Senator Clinton voted for it. That started the whole cycle of enforcement-only."

It took American Crossroads to bring up the fence vote, hiding in plain sight all cycle. Just months ago, Clinton told an Iowa audience that she had voted for strong fencing, as part of any immigration reform. (America Rising, another conservative group trying to sow discord on the left, captured video.)

The response from the Clinton campaign can be summed up as: Seriously? At Clinton's one-week-to-caucuses kickoff on Saturday morning, she was introduced by an SEIU organizer who told a harrowing story of being brought to the United States by smugglers from Mexico. Her endorsers generally argue that Sanders is playing catch-up, hoping that voters are more interested in rejecting the "establishment" than in political records.

"There are a lot of people who have become more skeptical over the last six, eight years, looking at Congress ... and want to say: a pox on everybody," said Rep. Xavier Becerra (D-Calif.), one of many surrogates who spent the weekend stumping for Clinton in Nevada. "On immigration, he's come to this a lot later than Secretary Clinton. Hillary Clinton speaks from experience about this."

American Crossroads is a nonprofit 527 political organization. Last week, the IRS granted tax-exempt status to American Crossroads GPS, a sister organization structured as a nonprofit, allowing it to conceal the identity of its donors.