WASHINGTON — President Trump’s trade war with Canada could intensify the headwinds Republicans are navigating ahead of the November midterms, with its effects poised to reverberate in northern battleground states with crucial Senate races. …The escalating beef with Canada stands to heighten voters’ economic worries and add to the GOP’s political challenge in dead-heat races, analysts said. …Trump’s new import bans on some Canadian goods are set to begin next week, a response to retaliatory tariffs Canada levied earlier this month. …Five of the nine states most likely to decide Senate control border Canada — Alaska, Ohio, Michigan, New Hampshire and Maine. Two more, Texas and Iowa, also do substantial trade with Canada. …“What’s weighing on the top of people’s minds is this general affordability crisis … and they realize that tariffs are another factor that is impacting affordability.”

• Related in the Guardian: Anger in Maine over Trump’s trade war with Canada