If Sanchez wins the Democratic nomination in the Texas primary next week and faces Republican Gov. Rick Perry, total spending by all candidates could climb to $75 million by November, according to Cal Jillson, a professor of political science at Southern Methodist University.
"It looks like Mr. Sanchez has spent $18 or $19 million now and this is just on the way to the ring ... he's still got to box," he said.
The big money will come if Sanchez wins the nomination next Tuesday and Perry faces the reality of a campaign against the wealthy Laredo businessman.
"The real spending is going to come when Rick Perry, the Republican, goes to the wealthy of Texas and says, 'Look, this guy has $600 million of his own money and he's going to spent a lot of it. I need your help,' and they will help," said Jillson.
Perry, a former lieutenant governor who became governor when Gov. George W. Bush was elected president, is making his first race for the office. He had no opposition in the primary race and will present a tough target for a Democrat in Republican Texas.
Sanchez, 59, made his millions as a banker, oilman and rancher in South Texas. His opponent in the primary is Dan Morales, 45, a Harvard-educated attorney and former prosecutor, state legislator and two-term state attorney general.
With his deep pockets, Sanchez has blanketed Texas with television advertisements whereas Morales, with much less money, has depended heavily on news coverage, debate appearances, and a better known name across the state because of his years in Austin.
In last Friday's debates, Morales accused Sanchez of trying to buy the election with his wealth. Sanchez said the spending was necessary to introduce himself to the voters and sell his program.
Sanchez has spent nearly $19 million on his campaign, according to financial reports filed Monday in Austin by the candidates. About $15 million was the candidate's own money. Morales, who entered the race late, has spent nearly $600,000.
Perry last reported $13.2 million in his campaign war chest, but his fund-raising activity is expected to accelerate after next Tuesday's primary.
The current spending record for a Texas governor's race was set in 1990 when Democrat Ann Richards and Republican Clayton Williams spent $50 million. Williams, a West Texas oilman, spent $22 million, the most by any single candidate for the office.
California still holds the spending record for a governor's race with $118 million spent by Democratic Gov. Gray Davis and other candidates in 1998.