In the first Presidential debate, Donald J. Trump and Hillary Clinton clashed over trade, the Iraq war, his refusal to release his tax returns and her use of a private email server, with Mr. Trump frequently showing impatience and political inexperience as Mrs. Clinton pushed him to defend his past denigration of women and President Obama. Hillary Clinton has been sliding in the polls over the past few weeks, and the race has grown uncomfortably close for Democrats who were expecting a landslide just over a month ago. So it’s certainly possible that Clinton will gain a few points in the polls from her debate performance, if the broader electorate agrees (or becomes convinced) that she won. Mr. Trump repeatedly interrupted Mrs. Clinton and at times talked over her throughout the 90-minute debate, making slashing attacks that surely pleased his Republican base but may have been off-putting to women and undecided voters. He also left unchallenged her assertion that he paid no federal taxes for years. For her part, Mrs. Clinton repeatedly chided Mr. Trump for bungling his facts while accusing him of hiding information about his debts to Wall Street and foreign banks. The initial indicators look good for Clinton, who was itching for some good news for her campaign.