It was primary day yesterday in Florida and Arizona — August primaries in some of the hottest parts of the country — and two veteran members of Congress were re-nominated, but by less than impressive margins. Squeakers, actually.

In Florida's 23rd congressional district Debbie Wasserman Schultz beat challenger Tim Canova in the Democratic primary in what a local TV station called a "big win." Not really. The margin was 57 to 43 percent, a solid if uninspiring margin for an incumbent in a general election, but a very weak showing by a longtime incumbent. Wasserman Schultz has represented the district since she first won in 2004, and has never had primary opposition before. It's a safe bet that just about every Democratic primary voter has been voting for her in general elections, which haven't been seriously contested in a district that voted 62 to 38 percent for President Obama over Mitt Romney in 2012.

Wasserman Schultz's weak showing owes something to her dismal record as Democratic National Chairman, which came to a halt at the beginning of the Democratic National Convention last month. She was strongly opposed by Bernie Sanders supporters, especially after revelations of DNC emails indicating the committee was tilting strongly against Sanders and toward Hillary Clinton. She was obviously considered expendable by the Clinton campaign, given her continual weak performance as a national spokesman for the party. She's a classic example of the Peter Principle in politics; she was promoted by the Obama White House, for reasons historians will struggle to explain, to a position for which she lacked the necessary talents.

Wasserman Schultz's opponent Tim Canova had strong support from Bernie Sanders, and Sanders supporters sent in plenty of money for his campaign. But he actually ran far ahead of Sanders in the 23rd district. I can't find a breakdown of the presidential primary vote by congressional district, but most of the district is in Broward County, which Clinton carried by a 72 to 26 percent margin, and the rest is in Miami-Dade County, which Clinton carried by a 75 to 24 percent margin.

The other close primary result came in the Arizona Republican Senate primary, in which John McCain beat challenger Kelli Ward by a 52 to 39 percent margin. Again, that's not a great result for an incumbent who is serving his 30th year in the Senate and was a House member for four years before that. Many Arizona Republicans have been angry at McCain for his active support of comprehensive immigration legislation and for his stance on some other issues. He lost Cochise County, which is on the border with Mexico and which several years ago was the scene of vast illegal border crossings and violent crimes committed by illegal immigrants. He also lost Mohave County, the home of many retirees. McCain has made clear his distaste for Donald Trump while technically supporting him; Mohave County voted 65 percent Trump in the Republican presidential primary.

McCain faces a serious general election opponent in 1st district Congresswoman Ann Kirkpatrick. McCain currently leads Kirkpatrick 45 to 37 percent in the RealClearPolitics average of recent polls, while Trump leads Clinton in the state by only 44 to 42 percent. There is probably some ticket-splitting going on. In Arizona as in Georgia, Republican presidential candidates have been carrying the states, despite large Democratic majorities from growing numbers of Hispanic (in Arizona) and black (in Georgia) voters, because college-graduate whites have been voting heavily Republican.

Some significant number, however, are likely not supporting Trump, who is also probably running weakly among Arizona's small but significant (circa 5 percent) Mormon population. McCain, on the other hand, is probably not running well with the elderly, in Mohave County and elsewhere, and it's not clear whether he can make inroads among Hispanics against a serious Democratic candidate. The odds favor McCain, but it's a race to watch.