American politics is complicated and weird

That's really all you can say about it.  Well, no, there is a bit more you can add...

The amount of effort needed to just get people to vote; the mid week timing of voting; the staggeringly enormous amount of money put into advertising; the racial divide in those who actually vote and the effort put into limiting the number who can vote; the routine claims of fraud in voting, particularly electronic voting:  to an outsider, these all appear as signs of a pretty damn dysfunctional system.   Yet, in the name of "freedom", the Right in particular seems to put much effort into preserving the aspects which make the rest of the world say "Jeez, can't you run a political system  better than that, America?"

The only potential up side to large wins (as seems to be expected) by Republicans is that I haven't noticed that the Tea Party side of the Right as being particularly prominent in the lead up to the election.  But I could be wrong on that...

Certainly, Phil Plait fears that a Republican win in the Senate will result in some ludicrous appointments which may affect climate change policy:

Nowhere is this more important than the Environment and Public Works Committee. A Republican win will almost certainly make James Inhofe, R-Oklahoma, chairman. This committee controls the Environmental Protection Agency, which is charged with addressing climate change and what to do about it. Inhofe is probably the most ludicrously adamant global warming denier in the Senate; he has called it a hoax and denies it to levels that would make the frothiest conspiracy theorists shake their heads in wonder.

Inhofe has indicated he will attack greenhouse gas regulators, so giving him control of this committee puts the "fox in charge of the henhouse" simile to shame.

Other committees will fare no better; as just one example Ted Cruz, R-Texas, could be chairman of the committee on science and space, and he also denies global warming. The irony is as excruciating as it is familiar.

What nauseating results they would be.

But on the upside, conservative over reach may well work in favour of the Democrats next time around:

Republican control of Congress could provide the stage for the next phase of the civil war in the GOP, with both wings jockeying for position ahead of the 2016 presidential election. Establishment and moderate figures like Senator Rob Portman want to improve the party's image—which, despite their projected success, remains awful—through constructive work. Hardliners like Representative Steve King and Senator Ted Cruz want to lay down a marker for an uncompromising conservatism, which they think will set the party up for victory in the presidential race, by obstructing any progress and investigating the administration. Many Democrats, as it happens, hope for the same thing. As their chances to hold on in the Senate have dimmed, many liberals' new fond hope is that Republicans will overreach and turn off voters, setting up a Democrat sweep of the White House, Senate, and perhaps even the House—an echo of what happened in 2012, following the GOP victories in 2010.