Mitt Romney on Tuesday secured US Republican Party's presidential nomination during a roll call vote at the party's national convention, and will challenge President Barack Obama in the coming presidential election.

Romney has passed the threshold of the required 1,144 delegates halfway through the roll call vote of delegates from 50 states, the District of Columbia and US territories, during its national convention at Tampa, Florida.

After passing the nomination, the convention is set to start its roster of speakers in the evening, including Ann Romney and New Jersey Governor Chris Christie, who will give the convention's keynote speech.

The convention is set to continue Wednesday with a speech from Romney's running mate Paul Ryan, and conclude Thursday with Romney 's speech accepting the nomination.

According to John Pickering, a political scientist with Florida 's Lynn University, the Romney campaign is counting on the convention to introduce Romney and his vision for the country to American voters, who usually become more aware of election after the party conventions in August and September, and start the last stretch of the campaign with a better footing in polls.

According to public opinion polls done before the Tampa convention, Romney and Obama are in dead heat, with the Obama campaign pounding Romney with a flood of negative ads in battleground states.

The Republican National Convention is tailored to shore up support for Romney, and the speakers were carefully selected. According to Gallup poll results released Tuesday, the American public mostly have favorable views of Ann Romney and Christie, who will have prominent speaking roles at the convention.