California is set to hold its Democratic and Republican presidential primaries today, with polls closing at 8 p.m. PT. The state's 169 delegates are up for grabs among the Republican candidates, including former President Donald Trump and former U.N. Ambassador Nikki Haley. Despite five Republicans having withdrawn from the race, they still remain on the ballot.

In the Republican primary, the winner-take-all format will determine the fate of the delegates. The candidate who manages to secure over 50% of the votes will receive all of the delegates. This adds an extra layer of intensity to the competition between Trump and Haley and magnifies the significance of garnering strong voter support.

On the other side of the political spectrum, President Joe Biden is facing challenges from Marianne Williamson and Rep. Dean Phillips in the Democratic primary. While Biden is the frontrunner, these long-shot challenges provide an opportunity for other candidates to gauge their support in the state.

California has adopted a mail-in ballot system, in addition to offering in-person voting, ensuring that all registered voters have the opportunity to cast their vote. This method of voting has gained popularity in recent years due to its convenience and accessibility, especially amid the ongoing pandemic.

Furthermore, the Green Party and Peace and Freedom Party candidates, Jill Stein and Cornel West, respectively, are also on the ballot. Their inclusion provides an alternative choice for voters seeking different political ideologies.

As the polls close, California's primary results will shape the dynamics of the presidential race. The number of delegates each candidate can secure will directly impact their overall chances of securing their party's nomination.

With a significant number of delegates at stake, all eyes are on California as the presidential candidates eagerly await the outcome of the primary.