(CNN) Support for Democratic House candidates has ticked up slightly to 50%, according to a CNN poll conducted by SSRS and released Wednesday.

The percentage of voters who said Democrats when asked which party they'll support in November was up three points since CNN's May poll, and Democrats have a sizable lead among voters who are most enthusiastic about voting. Forty-two percent of registered voters said they'll support the Republican candidate.

This week, Trump will embark on a week-long campaign tour taking him to the key states of Minnesota, Nevada, South Carolina, North Dakota and Wisconsin, rallying around Republicans in the 2018 midterm elections. Each of those states except South Carolina is home to a hotly contested Senate race.

The survey was conducted between June 14 and June 17, just as the stories of the US government separating children from parents trying to cross the border began to take over political conversations. It suggested wide disapproval of that practice, but a majority of Republicans favored President Trump and the White House in the matter.

The results of the "generic ballot" question had moved in the GOP's favor since early this year -- a 16-point lead for the Democrats in February dropped to a six-point edge a month later and dropped again in May to just three points. It has grown to an eight point lead for Democrats in the June poll, suggesting a slight rebound, with 50% of registered voters picking the Democrat and 42% going for the Republican.

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