A countywide sales tax increase and a separate sales tax hike in the city of San Diego both appeared to be falling short of the support each would need to pass based on early election returns Tuesday night. The county measure, Measure G, is a half-cent sales tax increase that would pay for rail, bus and road improvements. The city measure, Measure E, is a full-cent hike that could be spent on any city expenses. Everyone in San Diego County currently pays at least 7.75% in sales tax — the state rate of 7.25%, plus the half-cent TransNet surcharge that county voters approved to pay for transportation projects. If only the city measure passes, the rate in the city would be 8.75%. But if the county measure ends up passing, the base sales tax rate for all of San Diego County would rise to 8.25%. The rate would be higher in cities with local surcharges of their own. If both the county and city of San Diego measures pass, the rate within the city would jump from 7.75% to 9.25%. If only the county measure passes, the base rate countywide would be 8.25%. Both measures require approval by only a simple majority of voters.   Haney Hong, head of the San Diego County Taxpayers Association, said the measures’ performance was about voter trust. Sales tax measures in East County were leading in Tuesday night returns, he pointed out, but he said Measures E and G had failed because of a lack of trust in SANDAG and in San Diego City Hall. He said it was telling that Measure E appeared to be failing after its supporters had spent more than $1 million to promote it, while opponents spent a small fraction of that. Supporters of the county measure say the $350 million in essential transportation improvements it would fund would ease commutes and protect the environment by preserving natural habitats and keeping pollution out of local waterways. Critics say not enough of the money would go toward building roads and worry the lion’s share of the money could go to projects in the city of San Diego, leaving suburbs with less than their fair share. They also worry that it would steer more money to the San Diego Association of Governments, which already faces scrutiny for its management and processes. More than half the money would go toward public transit projects and local transit agencies, with the rest going toward local freeway projects and upgrades to local roads. The hike would double the half-cent TransNet sales tax that was initially approved in 1987 and extended in 2004. Voters rejected a previous attempt to double the rate in 2016. Some San Diego voters Tuesday balked at another tax hike. “I’m not super interested in raising taxes any more than they’re already going up,” Derek Dawson, 39, said while in line to vote in Mission Valley. “We pay so much in taxes already,” said his wife, Sophia. “Figure it out.” The city measure would generate about $400 million a year that could be spent on any priority, but city officials say they plan to spend a large share of the money shoring up decaying infrastructure. Without the money, supporters say deep budget cuts will be necessary — a scenario the city’s independent budget analyst has warned about several times. Most critics of the measure don’t dispute that the city needs the additional money, but they question whether city leaders would spend the windfall of cash on the right priorities. Critics note that the ballot measure does not place any restrictions on how the money could be spent. Restricting the revenue to certain uses would have raised the threshold for approval from a simple majority to two-thirds of voters. Some of those critics say it’s particularly difficult to trust city leaders in San Diego to spend the money wisely, citing the city’s troubled 101 Ash St. purchase. Two other city measures were leading in early results: Measure C, which would eliminate primaries in school board races with two or fewer candidates, and Measure D, which would bolster the Ethics Commission’s power. San Diego Union-Tribune staff writer Caleb Lunetta contributed to this report.