DETROIT — With a week to go before Michigan’s primary, national Democrats are spending big to help the far-right challenger to freshman Republican U.S. Rep. Peter Meijer, who voted to impeach former President Donald Trump. The Democratic Congressional Campaign Committee said it’s spending at least $425,000 in the Grand Rapids media market to run a TV ad over the next week about Meijer’s opponent, John Gibbs of Byron Center. The ad is a fake attack on Gibbs that could help promote his name among Trump’s base, claiming Gibbs is “too conservative” for west Michigan but also saying he was “handpic…