Viewer's Guide: Dem test in West; GOP seeks Southern comfort

Look for new clues in South Carolina's Republican primary about Donald Trump's appeal — and perhaps a narrowing of the GOP field.

[...] direct your attention to Nevada, where Democratic caucuses will render a Clinton vs.

Separate from the voting, Saturday also may well offer new intel about which candidates have the financial foundation to persevere as the primary and caucus calendar gets increasingly crowded.

Locked in a surprisingly tough fight, Clinton and Sanders are looking to Nevada, the first state with a sizable minority population, to send strong signals about the way forward.

Clinton, once thought to be the prohibitive favorite for the nomination, wants a heaping helping of reassurance from Nevada, whose diversity is thought to work to her advantage.

Exit polls will show whether Clinton got the union support she energetically courted, and who attracted the support of minority voters.

Don't forget his surprise second-place finish in Iowa, where he'd been ahead in polls. A strong Trump victory in South Carolina would feed into the larger question attached to his combative candidacy:

Ted Cruz used a strong ground game to outfox Trump in Iowa and is pinning his South Carolina hopes on more organizational mojo, dispatching 10,000 volunteers to turn out his supporters.

Exit polls will show how Cruz does with the state's large evangelical population, a key part of his coalition.

The Ohio governor's surprise second-place finish in New Hampshire breathed new life into his struggling candidacy.