Story highlights Former President George W. Bush will campaign for Republicans in competitive Senate races this summer

Bush won't attend the Republican National Convention in Cleveland next month

(CNN) Former President George W. Bush is lending a hand to vulnerable Republicans in competitive Senate races across the country this summer.

Bush has attended fundraisers for Arizona Sen. John McCain and New Hampshire Sen. Kelly Ayotte, and will attend upcoming events for Missouri Sen. Roy Blunt, Wisconsin Sen. Ron Johnson and Ohio Sen. Rob Portman, according to The New York Times

CNN has reached out to the Ayotte, Blunt, and Johnson campaigns for comment.

The 43rd president, who has said he isn't planning to participate in the White House contest nor attend the Republican National Convention in Cleveland next month, is throwing his support behind candidates whose down-ballot races might be impacted by presumptive Republican nominee Donald Trump.

Lorna Romero, a spokeswoman for McCain, confirmed that Bush held a fundraiser for the Arizona senator in Dallas earlier this week, adding that McCain was "honored" to have the former president's support in his re-election race.

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