Roy Moore is using the U.S. Chamber of Commerce's support for Sen. Luther Strange to tar his opponent as someone who favors amnesty for illegal immigrants as a new public opinion poll shows him losing ground in the special election for an Alabama Senate seat.

Moore, the former chief justice of the Alabama Supreme Court, asked supporters for help in an email fundraising appeal to fend off the chamber, which he described as "the establishment's top advocate for illegal immigration and amnesty in America." The chamber has launched a direct-mail and television advertising campaign in the state on behalf of Strange.

The amnesty charge against Strange came after recent interviews in which Moore appeared uninformed about federal immigration policy, including the Deferred Action for Childhood Arrivals program that Trump said he would rescind in March. Immigration hawks have been urging Trump for several days now to demand strict enforcement measures in any deal with Congress that preserves DACA.

Moore's latest online fundraising effort comes as JMC Analytics on Monday released a poll conducted Saturday and Sunday showing Moore ahead of Strange 47 percent to 39 percent, with 13 percent undecided. The firm's previous survey showed Moore leading Strange 51 percent to 32 percent, with 17 percent undecided.

The race could be even closer, given that the automated JMC telephone poll did not ring cellphones, and relied strictly on landlines (it had an error margin of 4.4 percentage points.) Last week, a poll produced for the pro-Strange group Senate Leadership Fund, the super PAC aligned with Senate Majority Leader Mitch McConnell, had the race effectively tied.

Another possible boost for Strange is coming from President Trump, who announced via Twitter on Saturday that he would visit Hunstville, Ala., three days before the Sept. 26 election to campaign for the senator. Trump is popular in Alabama and his endorsement should help move the needle for Strange, who was appointed to the Senate in January after Jeff Sessions resigned to become U.S. attorney general.

Huntsville, in northern Alabama, is a key battleground in the runoff and home to Rep. Mo Brooks, the conservative Republican who finished third in round one of the special GOP primary on Aug. 15 and on Saturday endorsed Moore. As Brooks did in the first contest, Moore is trying to use McConnell's support for Strange against him, while glossing over his differences with Trump.