Former Vice President Joe Biden returned to the campaign trail on Friday after a Democratic debate that largely reinforced his front-runner status for the party's presidential nomination, leaving his rivals searching for how to wrest away the top spot. The candidates who participated in Thursday night's debate in Houston, and those scrambling to try to qualify for next month's debate in Ohio, have less than five months to plead their case to voters before the first nominating contest in Iowa on Feb. 3, 2020. Biden on Friday held campaign events in Houston, where a day earlier he clashed with liberal rivals Elizabeth Warren and Bernie Sanders on healthcare, challenging the two U.S. senators to be honest about the cost of their plans. Biden came under fire from former US. Housing Secretary Julian Castro, who incorrectly accused the former vice president of forgetting what he had just in an exchange seen as an attack on Biden's age. And Biden's comments about racial inequality in schools prompted a rebuke from rival US Senator Cory Booker. "We are at a tough point right now, because there's a lot of people concerned about Joe Biden's ability to carry the ball all the way across the end line without fumbling," Booker said on CNN after the debate. After meeting students at historically black Texas State University in Houston on Friday — where the debate was held — Biden was asked about the barbs from Castro and Booker aimed at his age. He said Castro had gotten his facts wrong. Asked to respond to Booker, Biden said he will "carry the ball over the finishing line." But the top 10 Democratic candidates, sharing the debate stage for the first time after the party toughened the rules to qualify, also stressed their shared opposition to Republican President Donald Trump and scaled down some of the bickering that marked the first two debates this summer. Biden was sharper and more aggressive than in the earlier matchups, leaving him in a strong position as his rivals evaluate the best strategy in the race to pick a Democratic challenger to Trump in the November 2020 election. Aside from Biden, Sanders and Warren, none of the other 17 Democratic contenders is regularly hitting double digits in support in opinion polls. Several major events are on the campaign schedule in coming weeks. Biden, Sanders and at least three other candidates are expected on Monday to attend the Galivants Ferry Stump meeting in South Carolina. The next weekend, 18 candidates will attend the Polk County, Iowa, steak fry, a regular stop for presidential contenders, and at least 10 candidates will participate in a forum on thorny issues. The Democratic National Committee announced on Friday the next debate will be held in Westerville, Ohio, on Oct. 15 and possibly Oct. 16 depending on the number of qualifying candidates. At least one more candidate, billionaire activist Tom Steyer, has met the tougher qualifications for the next debate. — Reuters