**JEFF DENHAM** District 10: Middle Central Valley: Stanislaus-Modesto Even: Safeness of Seat 30% : Percent of Returns 5.3%: Percent of AGI $860 million SALT in 2014 294,000 tax returns in 2014 $16.264 billion AGI in 2014 $0.8552 billion deduction amount in 2014 47.1%: Income <$50K/year 19.1%: Poverty Rate 27.0%: White Collar 3.1% : Income >$200K/year
30% of tax returns in Jeff Denham's 10th California Congressional District in 2014 would have been penalized had state and local tax payments been added into the federal income tax base. The total increase in the tax base in 2014 would have been 860 million dollars. We do not have sufficient detail to produce a precise estimate of how much taxes would have gone up—the Trump administration could, if it wanted to—but the rough ballpark number is 210 million: the Republican tax bill will, if enacted, take 210 million dollars a year out of the incomes and spending of Jeff Denham's constituents.
The relatively poor (for California) Central Valley 10th contains only a small slice of people who are possible beneficiaries from the tax bill: 3.1% of returns in 2014 reported adjusted gross incomes greater than 200,000 dollars a year. But by the same token that was one-ninth of the number of returns that itemized SALT. While incomes, and thus state income taxes, and property taxes are lower in the Central Valley than in highly-prosperous booming coastal California, adding people's state and local taxes to the federal income tax base would still take a substantial bite out of their budgets.
The evenly-split white-Hispanic Central Valley 10th should be a competitive district. Thus one would imagine that Jeff Dunham would believe he could not risk further eroding the allegiance of the highly enterprising and prosperous traditionally-Republican California upper middle class. While its concerns are not the Republican Party's core concerns any more, and it is leaking away, Jeff Dunham should not want to accelerate the process.
Dunham thus appears to perhaps be another one of those who has decided that the district will flip sooner rather than later, especially given the ongoing chaos of the Trump administration and the possibility of an anti-Republican wave election in 2018. Thus he may have become another who has shifted the constituents he serves from the state, district, and constituents of California to his constituents among the House leadership and on K Street. Otherwise, his support for the tax bill appears inexplicable as a matter of either politics or policy.
(Assuming, of course, there has not been a programming mistake in moving from zipcode-level IRS Statistics of Income to Congressional District level. Programming mistakes are easy to make.)