The front-runners for the nominations in the US presidential race are aiming to extend their leads on Saturday.
Republicans are holding caucuses or primaries in four states, with Democrats voting for their candidate in three.
Former Secretary of State Hillary Clinton leads the Democrats’ contest while billionaire Donald Trump is ahead in the Republicans’ race.
Efforts by Republicans to slow Trump’s march have so far failed.
At a televised debate on Thursday, his main rivals for the nomination, Ted Cruz and Marco Rubio, launched a series of attacks on him.
Mitt Romney, the 2012 Republican nominee, earlier accused the businessman of bullying, greed and misogyny. Trump dismissed Romney as a “failed candidate”.
Two days earlier, on Super Tuesday, Trump won seven of the 11 contests.
At Saturday’s caucuses in Kansas, Kentucky and Maine, as well as the Louisiana primary, Trump will be seeking to cement his lead.
The more states pick him, the more delegates he claims. Republican candidates need 1,237 delegates to win the nomination.
Trump is 908 delegates short; 155 are available on Saturday.
In a number of states, the evangelical vote could prove decisive on Saturday. While Cruz, the Texas senator, has support among the evangelical base, Trump has succeeded in drawing some of their support in previous contests.
On Friday, Ben Carson, who was at one point a Republican front-runner, dropped out of the race.
Democrats will turn out in caucuses in Kansas and Nebraska, as well as a primary in Louisiana.
Clinton heads the race, and has in recent days started targeting Trump in her speeches, instead of her fellow Democratic candidate Bernie Sanders.
Polls have indicated she has strong support in Louisiana among black voters, but analysts suggest the race between Clinton and Sanders may be close in other states on Saturday.
One hundred and nine delegates are available in the Democrat races on Saturday. Clinton needs a further 1,137 delegates to win the nomination.