Indiana is an important test for Trump in his quest for 1,237 delegates.
Clinton's lead is down from March, but she still posts a 22-point advantage
Clinton leads by 2 points in a state Republicans have won in seven of nine presidential elections.
Two national polls found her lead over Sanders is narrowing.
But the pollster warned that Trump's support has slipped in recent days.
Poll comes as Trump drops plans to attend CPAC to campaign in Kansas.
The Texas senator is ahead of Trump by 9 points ahead of Super Tuesday.
Illinois poll shows Clinton with 51 percent support in Illinois.
A new poll shows Bernie Sanders ahead of Hillary Clinton in West Virginia.
Poll shows Trump in lead in Massachusetts, with Sanders and Clinton tied.