Also to my understanding, Vigdís was the first. After her there have been several. In most times it’s hard to say how much of the vote in a particular election has been influenced by the party, or coalition of parties and how much by personal merit. And of course there can be other forces behind an elected politician. I’ll try to give you an example I’m familiar of.
Here in Finland we have had female president elected by popular vote since 2000. She has been elected by popular choice twice, besides 2000 also in 2006. Is Tarja Halonen’s success then the product of her personal merits, or because of the so called party machine? One could say party, since she is the third consecutive president from the Social Democratic Party, SDP’s candidate has won the presidency every time since 1982, despite the party usually getting less than 25% in parliamentary elections. However this has not really been because of some powerful party machine, but more because of right wing candidates’ infighting, and also because of actual personal merits.
Halonen herself had been member of parliament since 1979; after 1987 she was already four years a minister, mainly for social matters. Then in 1995 she became the Foreign minister and held that position until elected president. SDP’s then president Ahtisaari had become unpopular while Halonen was a popular minister so early in 1999 it was decided that she would be party’s new candidate. No primaries etc. were held that time as she was basically the only one really interested. Then the well led EU Council Presidency made the Foreign minister even more popular, and another party, Left Alliance, also gave her its support. So in the first round of elections Halonen already got 40% among seven candidates, and won the second round with 52%, even though SDP and the Left, if put tugether, had got under 34% of the vote in the last parliamentary elections. And as she has been a very popular president, she won the second term with even higher numbers.
Another example here is the first serious female contender for presidency, Elisabeth Rehn, who lost the 1994 election in runoff. But she was the candidate of Swedish People’s Party who normally only get around 5% of the vote in parliamentary elections, and all the large parties each had their own candidates running. Even then Rehn, who was the first female Defense minister, member of parliament since 1979, popular and generally viewed as charismatic and competent, got 22% of the vote in the first round, and lost the second round with 46%. Of course this reflects a very well run campaign, but at least there was no big party machine running it, it was all about personal merit.
Also, like jjimm said, the power is not necessarily held by the person who is called president, and the head of govenment is not necessarily the same as the head of state. Again in Finland, we have an odd semi-presidential system. The old constituency pretty much left undefined the exact powers of president in relation to parliament and prime minister. So while earlier presidents were careful not to get too much power, Kekkonen in 60’s and 70’s took all he legally could, then the SDP presidents gave away most of these powers and now the new constitution limits them anyway. So today prime minister clearly holds more power in practice than the president in Finland.
One more; that the office is named “president” is no reason that the holder has to be elected by popular vote. For example Finland chose the president via electoral college until 1980’s. And this worked independently, unlike the one in the US where electors almost always vote for the guy who got plurality in their state. In our version, people voted for party and other elector lists in their own constituencies, and then the elected electors, everyone free to choose, though parties usually coordinated them, voted for president.
Anyway, of the currently serving female presidents, Chile’s Michelle Bachelet and Argentina’s Cristina Fernández de Kirchner probably have the most actual power. They both got elected by popular vote, though I’d say that only Bachelet won by personal merit while Kirchner’s victory was because of her husband and predecessor’s (these two are the same guy…) support.