With Election Day approaching, key US Senate races are growing increasingly contentious.

In Alaska, federal prosecutors are investigating claims that Democrats backed an independent candidate with the same name as the Republican incumbent, raising concerns about voter confusion.

Meanwhile, candidates across battleground states are trading accusations over religion, immigration and extremism.

Although President Donald Trump is not on the ballot, debates over his policies on the economy, foreign affairs and migration are shaping campaigns nationwide, with control of Congress at stake.