Female candidates have been the big winners in a dozen primaries in the United States, where voters have been picking Democratic and Republican candidates for mid-term elections in November.
In California, two former company bosses, Meg Whitman of eBay, and Carly Fiorina of Hewlett-Packard, won the Republican nominations for state governor and US senator respectively.
Senator Blanche Lincoln (Dem) won a high-profile battle in Arkansas, confounding pundits who said she would lose amid anti-incumbent feeling.
The two-term senator narrowly defeated Lt Governor Bill Halter.
In California, Ms Whitman will be the Republican candidate to replace Governor Arnold Schwarzenegger, setting up a contest against former Democratic Governor Jerry Brown.
Ms Whitman - who spent $US70 million of her own money on her campaign - is the first woman nominated for governor by of the state Republican Party.
Ms Fiorina will be the Republican candidate to challenge Democratic Senator Barbara Boxer in November.
In Nevada, Republicans chose Sharron Angle, a conservative, as their candidate against Senate Majority Leader Harry Reid, (Dem) whose popularity in his home state has nosedived.
The BBC reports the mid-term elections in November will be viewed by many as a referendum on Mr Obama's presidency.
Analysts say the possibility of the Democratic Party losing control of one or both houses of Congress cannot be ruled out.
The Democrats currently control 59 seats in the Senate (including two seats held by independents) and have a majority of some 40 seats in the House of Representatives.
All 435 House seats are up for election as well as about a third of the Senate's 100 seats.