Surging GOP candidate Marco Rubio just picked up 2 endorsements in a key early state

Sen. Marco Rubio (R-Florida) is rolling out additional support for his presidential campaign from Iowa, the influential first-caucus state.

Rubio's campaign told Business Insider that a pair of Republican state senators endorsed Rubio's increasingly competitive White House bid on Wednesday.

Both lawmakers - state Sens. Dan Zumbach (R) and Tom Shipley (R) - had previously endorsed Wisconsin Gov. Scott Walker (R).

Earlier this year, Walker had appeared to be a front-runner in Iowa, but his support and fundraising lagged. Walker suddenly exited the race in September.

In their statements, Zumbach and Shipley hailed Rubio's campaign themes, particularly his vision for a "New American Century."

"As a farmer and small business owner, Marco Rubio's vision for a New American Economy will create jobs and world trade and I am proud to support him," Zumbach said. "Marco will make our country vibrant in the 21st Century and I look forward to helping him in Iowa."

Shipley added, "Marco Rubio is a generational leader who will fix how Washington operates and I am proud to endorse him for president. Marco's uplifting plan for a New American Century is exactly what we need and I look forward to helping him win the Iowa Caucuses."

Rubio's campaign has surged in recent weeks as other former front-runners, notably former Florida Gov. Jeb Bush (R), stumbled in the polls and front-runner Donald Trump has maintained his dominance.

The latest Republican primary surveys have generally found Rubio competing for second place with Sen. Ted Cruz (R-Texas) and retired neurosurgeon Ben Carson - with all of the other candidates in low-single digits.