Washington CNN  — 

Donald Trump has established a clear lead over Ted Cruz in Iowa, with just a few days left until the caucuses, while Bernie Sanders has narrowed the gap with Hillary Clinton there, according to new polls.

Sanders has also expanded his lead over Clinton in New Hampshire, while Trump continues to lead the GOP field there, according new NBC News/Wall Street Journal/Marist polls released Thursday morning.

“Trump is positioned to run the house in these first three states. His supporters are committed and plan to turn out,” Lee Miringoff, director of the Marist College Institute for Public Opinion, in a statement accompanying the poll release. “Will it happen? The answer depends on when or if anti-Trump sentiment will coalesce to interrupt his march to the nomination.”

In Iowa, Trump leads Cruz 32% to 25%, followed by Marco Rubio with 18% Ben Carson with 8%. Clinton has held onto her lead there, but just narrowly, besting Sanders 48% to 45%.

The results are consistent with other polls released recently, just as would-be caucus attendees are firmly tuned into the race.

RELATED: CNN/WMUR Poll: Sanders trouncing Clinton in New Hampshire

In New Hampshire, Sanders is beating Clinton 57% to 38% and Trump is dominating the Republican field with 31% support. He’s followed by Cruz with 12% and Ohio Gov. John Kasich and Rubio tied at 11%

For now, Clinton’s southern “firewall” appears to be easily holding in South Carolina, where she beats Sanders 64% to 27%, with strong backing from African-American voters. Trump is winning the Palmetto State with 36% support there, followed by Cruz with 20% and Rubio with 14%.

The Iowa poll surveyed 426 likely Democratic caucusgoers between January 24-26 for whom the margin of error was plus or minus 4.6 percentage points. It also included 450 likely Republican caucusgoers and had a margin of error of plus or minus 4.7 percentage points.

The New Hampshire poll surveyed 568 likely Democratic primary voters and 612 likely Republican primary voters between January 17-23. The margin of error was 4.1 percentage points for the Democrats and 4.0 percentage points for the Republicans.

The South Carolina poll, also conducted January 17-23 surveyed 718 likely Republican primary voters and 446 likely Democratic primary voters. The margin of error was 3.7 percentage points for the Republicans and 4.6 percentage points for the Democrats.