Sen. Cory BookerCory Anthony BookerTo strengthen our democracy, we need to remove obstacles that keep students from voting Members of Congress demand new federal gender pay audit The Hill's Morning Report — Can the economy help Republicans buck political history in 2018? MORE (D-N.J.) attacked Rep. Tom CottonThomas (Tom) Bryant CottonSenate GOP tries to defuse Trump border crisis GOP senators drafting legislation to keep immigrant families together Hillicon Valley: Supreme Court takes up Apple case | Senate votes to block ZTE deal | Officials testify on Clinton probe report | Russia's threat to undersea cables | Trump tells Pentagon to create 'space force' | FCC begins T-Mobile, Sprint deal review MORE's (R-Ark.) votes against federal disaster relief funding at a weekend campaign event for Cotton's opponent, Sen. Mark PryorMark Lunsford PryorMedicaid rollback looms for GOP senators in 2020 Cotton pitches anti-Democrat message to SC delegation Ex-Sen. Kay Hagan joins lobby firm MORE (D-Ark.).

Booker knocked Cotton for voting against federal funding to help New Jersey and New York after Hurricane Sandy, arguing Cotton broke with a long bipartisan tradition of finding money to help communities recover.

"I'm frustrated and worried that Mark Pryor's opponent in this race stands against that tradition, not a Democrat or Republican tradition, but stands against that American tradition that we take care of our own," Booker said in a Saturday news conference at the state Capitol, according to The Associated Press. "That we are a nation indivisible, that when a crisis attacks our soil — be it a natural disaster or a terrorist attack — we stand up for each other and are there for each other."

Pryor has been revving up his criticism of Cotton's vote on Sandy relief ever since Arkansas was ravaged by a series of tornadoes in late April that killed a dozen people near Little Rock and caused millions of dollars in damage.

"Basically, what he was doing was, he was voting to say that we don't want to have those resources available when we need them," Pryor said at the event.

Cotton has argued the bill for Sandy relief was larded up with spending on other projects and voted against a later bill for flood insurance for victims of the storm because it didn't have offsetting spending cuts.

"Like all Americans, I offer my prayers and sympathy to our fellow citizens when they fall victim to natural disasters, which is why I support annual FEMA funding and the traditional disaster-aid process," Cotton fired back in a statement. "What I will not support are Washington politicians who take advantage of a terrible tragedy by larding up emergency relief packages with pork projects that aid those politicians' re-election campaigns instead of aiding storm victims."

— This post was updated at 1:40 p.m.