RECREATIONAL pot is legal in Colorado. So, from this week, is gay marriage. So you might think liberals would find it easy to win elections here. Yet Barack Obama is so unpopular in Colorado that when Mark Udall, a Democratic senator fighting for re-election, skipped one of his own fundraisers at the last minute, everyone assumed it was because Mr Obama was to headline it.

This is quite a turnaround. Like several Democrats in swing states, Mr Udall was first elected to the Senate on Mr Obama’s coat-tails in 2008. Now, like practically every vulnerable Democrat, he is trying to distance himself from the president—something footage of the two men hugging might have made trickier.

The Republican Senate candidate in Colorado, a young, charismatic congressman with a Mona Lisa smile called Cory Gardner, calls Mr Udall a rubber stamp for Mr Obama. Mr Udall calls Mr Gardner “extreme” (and indeed, in 2012 he was named as one of the most conservative members of the House of Representatives). But Mr Gardner has run a strong campaign in a state that has moved leftward in recent years, as more young people and Latinos have moved in. With less than a month to go, the race is a dead heat. If it flips, so, probably, will the Senate (see chart).

The Rocky Mountain State wasn’t always swing territory. Before Mr Obama, no Democratic presidential candidate except Bill Clinton had carried it since 1964. But in recent years a Democratic state legislature has pushed through a series of liberal bills, for example to enforce background checks for gun-owners and allow in-state college tuition for illegal immigrants. Progressives in college towns such as Boulder applaud, but conservatives in other parts of Colorado are fed up. “There’s no big issue in this race,” says Floyd Ciruli, an independent pollster. “It’s become entirely about accusing people of being extremists or puppets of Obama.” Mr Udall has tried to rally female voters by accusing Mr Gardner of being a footsoldier in the so-called Republican “war on women”. About half of Mr Udall’s TV spots have focused on abortion and contraception. A voice-over in one said Mr Gardner had sponsored a bill to “make abortion a felony, including in cases of rape and incest” and had “championed an eight-year crusade to outlaw birth control”. The ad was referring to Mr Gardner’s support for a so-called “personhood” ballot measure, which would have endowed fetuses with the same rights as people from the moment of conception. No state has ever passed such a measure—Colorado rejected it by 71% to 29%. And were such a law to pass, it would quickly be struck down by the courts. But critics say that, if “personhood” became law, it might make contraceptives such as intra-uterine devices illegal, because they could prevent the implantation of a fertilised egg.

Inconstant Gardner

In March Mr Gardner announced he had changed his mind; he said he hadn’t realised the “personhood” measure would restrict access to contraception, telling the Denver Post: “I don’t get everything right the first time.” Mr Gardner then announced in June that he favoured allowing birth-control pills to be sold without a prescription. Republicans in several states have aired the same proposal. They say it would make it easier for women to obtain contraception, and would lower the overall cost, since it would not involve a trip to a doctor. Democrats retort that since many insurance policies do not cover over-the-counter drugs, the cost borne by the women themselves would rise.