AUSTIN, TX - APRIL 1: Rep. Beto O'Rourke (D-TX) speaks to a group of supporters at Scholz Garten on April 1, 2017 in Austin, Texas.   O'Rourke announced his plan to run for Ted Cruz's Senate seat on Friday and launched his campaign with a four-city tour of Texas. (Photo by Drew Anthony Smith/Getty Images)
Drew Anthony Smith/Getty Images North America/Getty Images
AUSTIN, TX - APRIL 1: Rep. Beto O'Rourke (D-TX) speaks to a group of supporters at Scholz Garten on April 1, 2017 in Austin, Texas. O'Rourke announced his plan to run for Ted Cruz's Senate seat on Friday and launched his campaign with a four-city tour of Texas. (Photo by Drew Anthony Smith/Getty Images)
Washington CNN —  

The battle over a US Senate seat in Texas continues to heat up after a statewide poll released Wednesday shows Democratic candidate Beto O’Rourke just 4 points behind Republican incumbent Sen. Ted Cruz.

The NBC News/Marist Poll finds Cruz with 49% support compared with O’Rourke’s 45%, and 6% of voters undecided.

If O’Rourke were to pull off a victory, he would be the first Democrat to win a statewide seat in Texas since 1994, in a race that CNN has labeled as “Likely Republican.”

According to the poll, Latinos make up 20% of the registered voters in the sample, and they favor O’Rourke with 53% support, while only 42% support Cruz.

The Texas poll was just one of several released on Wednesday, with eyes on races across the country ahead of a contentious midterm season where Republicans are in jeopardy of losing their congressional majority.

Some of those polls held warning signs for Democrats.

A Marquette Law School Poll found a tightening race between Democratic Sen. Tammy Baldwin and Republican Leah Vukmir. Baldwin, according to the poll, had 49% support, Vukmir had 47% support and 3% said they did not have a preference.

Another Midwest senator up for re-election is Democratic Sen. Amy Klobuchar of Minnesota. A Suffolk University/St. Cloud Times poll released Wednesday has Klobuchar leading with 54%, while her Republican challenger, Jim Newberger, has 34% support.

“Senator Amy Klobuchar is setting a torrid pace for Democrats in Minnesota,” said David Paleologos, director of the Suffolk University Political Research Center in Boston, according to the news release. “Her popularity may impact other Democrats on the ballot, who can benefit from her ‘Klobuchar Coattails.’ “

A Quinnipiac University Poll also released on Wednesday finds the margin beginning to shrink between Democratic Sen. Robert Menendez and his Republican challenger, Bob Hugin.

The poll shows Menendez with 43% support and Hugin with 37%. In a March 13 poll from Quinnipiac, Menendez had 49% support while Hugin had 32%, a news release from Quinnipiac noted.

Last year, Menendez faced charges of conspiracy, bribery and honest services fraud related to allegedly abusing the power of his office, however the trial ended in a mistrial with the jury deadlocked.

According to the Quinnipiac University Poll, 49% of New Jersey voters said Menendez was “involved in any serious wrongdoing,” while 31% said they hadn’t heard enough to decide.

“As Sen. Robert Menendez sees his once dominant lead whittled down to single digits, New Jersey voters are sending a clear message. They are troubled by the ethics cloud hanging over him,” Mary Snow, polling analyst for the Quinnipiac Poll, said in a statement.