Donald Trump faces a must-win presidential debate on Sunday night after a torrid 10 days left him trailing Hillary Clinton in opinion polls in key battleground states.  With early voting already under way, the Republican candidate has seen his September polling gains wiped out and is fast running out of time to shift momentum back his way in the race for the White House.  A live debate always raises the prospect of the ill-disciplined Trump allowing Clinton to get under his skin and making a gaffe that could throw his campaign into disarray. The bombastic billionaire stirred fresh controversy on Friday when, in a meeting with a union representing border patrol agents, he floated a new conspiracy theory, saying that immigration officials were trying to expand the pool of American voters.  Trump directly challenged the media to report his remarks, which followed comments by union vice-president Art Del Cueto in a meeting in Trump Tower in New York. Del Cueto told the celebrity businessman: “Immigration is so tied up with trying to get the people who are on the waiting list to hurry up and get them their immigration status corrected ... so they can go ahead and vote before the election.”  “Big statement, fellas,” Trump said, motioning to reporters. “You’re not going to write it. That’s huge. But they’re letting people pour into the country so they can go and vote.”  Clinton was widely judged the winner of the first debate. Both candidates face a test of stagecraft on Sunday in what has become popularly known as a “town hall” format for their second showdown in St Louis, Missouri, moving around a stage with handheld microphones as they field questions from voters.  The first town hall debate was held during the 1992 election. As a voter stood to ask George H W Bush about the national debt, the president glanced down at his watch, an image that seemed to reinforce criticism that he lacked empathy. Clinton’s husband Bill won the election.  In 2000 George W Bush was answering a question on leadership during such a forum when Vice-President Al Gore rose from his chair and walked peculiarly close to his Republican rival. Bush turned and gave Gore a nod and a smile, prompting audience laughter.  Rick Tyler, a political analyst and former spokesperson for Republican primary candidate Ted Cruz, said of Trump: “From what I can tell from the polls, his prospects in the election are bleak. He’s going to need a game-changing win in the debate if he’s going to stand any chance in November.”  But the town hall format will not necessarily suit him. “He’s just not an impressive performer when it comes to answering people’s questions,” Tyler added. “He’s not grounded in policy, foreign or domestic. He doesn’t give a lot of thought to issues. He’s missing empathy; when someone asks a question, he has trouble connecting at their level.  “I think she’ll win it. She has so much more experience at this. She comes across as cold, but she has more skills than he does.”  According to the Real Clear Politics polling average, Clinton is currently 4.5 points ahead of her Republican opponent in a two-way race, a poll position that would translate to at least 237 of the 270 electoral college votes she needs to win firmly in the bag, with 165 for Trump and 136 to play for.  There is a glimmer of hope for Trump, however, in polls that show him down but not out in the key swing states that are likely to determine the election outcome, and that suggest his dismal showing in the first debate had only a marginal impact.  A survey by Quinnipiac University on 8 September, taking smaller parties into account, gave Clinton a 46-41% lead over Trump in Florida, 46-43% in North Carolina and 45-41% in Pennsylvania. It had Trump up by 47-42% in Ohio.  Peter Brown, assistant director of the Quinnipiac University Polling Institute, told a conference call on Friday: “Debates are obviously the kind of events that make it possible to have election-changing influence. Right now it’s a pretty fair consensus of our polls and other people’s polls that Secretary Clinton seems to have a small lead, maybe three, four, five points nationally.  “In some of the swing states, there’s some results that are just plain different. So we enter the next debate with Mrs Clinton slightly ahead but not gigantically ahead. The other interesting question is how the debates will affect the presidential race.”  The Quinnipiac survey found that likely voters said by margins of more than two-to-one that Clinton won the first debate. Brown added: “The poll taken right after that debate happened found there had been a relatively small increase in support for Mrs Clinton, not nearly as large as one might expected given the overwhelming consensus that Mrs Clinton won that debate.”  Brown noted that a large percentage of the electorate in states such as Florida and Ohio will have voted by election day due to early-voting provisions in those states. This is likely to intensify pressure on Trump to arrest Clinton’s momentum.  Ahead of Sunday, Trump has reportedly reviewed video of the first presidential debate, and his aides have stressed a need to stay calm and not get riled. He limbered up at a real town hall on Thursday night in New Hampshire but did not interact directly with the audience, taking questions only from a moderator.  Trump told the small crowd: “This isn’t practice; this has nothing to do with Sunday. This isn’t practice, we just wanted to be here.”  And he made fun of Clinton for preparing in depth. “I said, ‘Forget debate prep.’ I mean, give me a break. She’s resting. She wants to build up her energy for Sunday night. And you know what? That’s fine. But the narrative is so foolish.”  Trump was joined by New Jersey governor Chris Christie, who performed well in the town hall format during his failed presidential campaign and is helping the nominee get ready.  The Clinton camp has said it expects Trump to have done more homework this time. “But even if he does show up a little more disciplined than last time, I don’t think he’ll get a second chance to make a first impression,” Clinton spokesperson Brian Fallon said.
Second debate’s town hall format may pose challenge for Trump, who struggles with policy and empathy for voters, while Clinton thrives on the political stage