Trump’s summer campaign priority: Target red-state Democratic senators

In the coming weeks, the strategy will also take Mr. Trump to North Dakota, Montana, Missouri, Indiana and West Virginia — all deeply red states he won handily in 2016 with endangered Democratic senators. It does not include immediate plans to go to Florida, Michigan, Nevada or Ohio, although those states could be added to the president’s itinerary as the November contests draw closer, the officials said, and his schedule is likely to fill out with well over a dozen stops each month.

White House officials, who have pushed to keep Mr. Trump from getting involved in primary races, said that the focus on the six red states before primaries have taken place will give him a chance to bloody the Democrats there while Republicans are still settling on their nominees.

On Tuesday morning, Mr. Trump previewed a combative political message, charging that the special counsel investigating Russia’s interference in the 2016 presidential elections — and whether his campaign played any role — was a Democratic-run scheme to steal the 2018 congressional contests.