Rupert Murdoch has donated $1m to the Republican Party in advance of the midterm elections in November.

The media magnate supported and praised Barack Obama from early on in the primary season in 2008, but has now turned to the Republicans, it seems. News Corporation commented that it supported the Republicans' "pro-business agenda" and felt that the party was aligned with "our priorities at this most critical time for our economy".

The Murdoch-owned titles the Wall Street Journal and New York Post, as well as Fox News, have long been editorially aligned with the Republicans, and now Murdoch himself is following suit.

Crucially, the donation was made to the Republican Governors Association (RGA). Although the main focus so far has been on the House and Senate races, where unusual candidates and unusually large predicted gains have drawn media attention, the GOP also looks likely to gain a majority of governorships. There are 37 governorships being contested this year, the most ever in a single election.

Unlike national political parties and individual candidates for the House and Senate, gubernatorial campaigns can accept unlimited donations from corporations. News Corporation has clearly taken advantage of this in choosing the destination of its funds.

Kansas, Iowa, Michigan, Pennsylvania, Tennessee, Wyoming and Wisconsin all look likely to swing to the Republicans, and in several more states the race is too close to call. A combination of governing-party implosion and the after-effects of the recession will probably allow the Republicans to take six or seven governorships overall, despite a few potential wobbles by GOP candidates in Connecticut, Hawaii and Minnesota.

This is by no means the first time that Murdoch has switched political allegiances to favour his own business interests. In the UK, his famed switch from Conservative to Labour stands out, as does the less prominent switch back for the most recent general election.

Targeting the funding at gubernatorial races rather than those for the House and Senate is undoubtedly designed to further the "pro-business agenda" identified by News Corporation. Although there are variations with individual state constitutions, many governors wield immense power over budgeting and local government appointments, enabling them to set the agenda for regulation and taxation in their state. It increasingly seems that many state legislatures will also swing to the Republicans, and so new governors aren't likely to have much trouble passing legislation once they're in office.

According to information released through the Internal Revenue Service, the RGA has raised $58m in the first half of this year to the Democrats' $40m. In addition to benefiting from anti-incumbent sentiment and recession backlash, the RGA has received significant donations from health insurance giants such as Wellpoint, in response to the passage of the Democrats' health-care bill earlier this year.

Across the US, the midterms are going to be a useful political bellwether for how the parties are really faring post-2008. Murdoch's donation signals perhaps the most intriguing area: how many governorships can the Republicans take?