Rep. Zoe Lofgren, the California Democrat backing Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE, bashed Bernie Sanders Bernie SandersMcConnell accuses Democrats of sowing division by 'downplaying progress' on election security The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Why Democrats must confront extreme left wing incitement to violence MORE as failing to accomplish much in Congress and accused him of helping to "kill" immigration reform in 2007.

"You look at someone's achievement level and there's very little to show in terms of legislative achievement. I don't want to be snarky about it but the truth hurts. Hillary has accomplished a lot, both in the Senate and as secretary of State."

The former chairwoman of the House Judiciary Committee's Subcommittee on Immigration and Border Security, she lamented that Sanders worked to scuttle immigration reform in 2007, an issue that Clinton campaign surrogates have repeatedly brought up to barb the Vermont senator.

It's a vital issue in Saturday's Democratic Nevada caucuses, as Clinton looks to edge out Sanders's late surge in the state. Her campaign has relied on strong support from minority voters, which makes a state like Nevada with a substantial minority voter population a test of whether that support will hold.

Sanders has repeated on the trail that he sided with Hispanic groups who believed the guest worker program in the bill amounted to "slavery." But the Clinton campaign blasted out his official 2007 statement on that bill to reporters, which doesn't mention that argument.

Instead, Sanders's statement argued that the bill would have "driven down wages and benefits for U.S. workers by letting employers recruit lower-paid foreign guest workers." That prompted unions like the AFL-CIO to also express concerns that the bill would hurt labor.

"Bernie did not stand with us," Lofgren said, "and we have never gotten that close again."

"I served with Bernie. Almost everybody who has served with Bernie is supporting Hillary," she said on MSNBC inside a Nevada caucus site in Henderson.