President Trump’s nominees for key ambassador posts on Thursday faced questions from Democratic senators concerned about the economic and diplomatic ramifications of the administration’s aggressive use of tariffs on close trading partners, particularly Canada. During a confirmation hearing held by the Senate Foreign Relations Committee, Trump’s nominee to represent the U.S. in Canada, former Republican Rep. Pete Hoekstra (MI), defended what he characterized as the president’s efforts to pursue “fairer, freer” trade in responses to questions about Trump’s tariffs and...