President Donald Trump's late campaign blitz targeting immigrants has rallied the Republican base of white working-class voters, helping to curb the Democratic advantage heading into Tuesday's midterm elections for Congress.

The election-eve NBC News/Wall Street Journal poll shows Democrats leading by seven percentage points, 50 percent to 43 percent, among likely voters. That's down from a nine-percentage point lead last month.

That slightly narrowing reflects rising interest in the election from the foundation of Trump's support: White men, especially older, less educated, less affluent ones in small towns and rural areas. Most noteworthy for a mid-term election, the 2018 campaign has seized the attention of voters at presidential-campaign levels — and Trump has helped Republicans wipe out the advantage Democrats held earlier in the campaign.

"There has been some method to his madness," said Republican pollster Bill McInturff, who conducts the NBC/WSJ survey with his Democratic counterpart Peter Hart. "The base is coming home."

The results presage the possibility of a split verdict on Tuesday. With many battleground House races taking place in more affluent suburbs, the unusual Trump-era advantage Democrats continue to maintain among college-educated whites — especially women — represent a strong sign for their prospects of gaining or exceeding the 23-seat gain they need to recapture the majority.