Senate Republicans on Monday said they could pick up at least six seats in this fall's elections, and compete in seven more.

In a memo, the National Republican Senatorial Committee (NRSC) predicted that all Republican incumbent senators would win reelection, and that GOP candidates would likely hold onto open seats previously held by Republicans.

"Every Republican incumbent running for reelection will win, as there is not a single state in which an incumbent Republican nominee is facing a substantial threat," NRSC executive director Rob Jesmer said in a memo. "We also strongly expect to hold every Republican open seat."

In the field of 13 competitive races where Republicans could win a seat, Jesmer used the word "win" in connection to six, with more careful language toward the other races.

"We assume their ability to predict outcomes in the general election will be as accurate as it was in the primaries," said Eric Schultz, a spokesman for the Democratic Senatorial Campaign Committee (DSCC).

Democrats pointed to polls in Delaware, California, Kentucky, Missouri, Washington, and Pennsylvania as evidence that their candidates are becoming more competitive -- if not running ahead -- of GOP candidates.

Jesmer predicted outright victory for Gov. John HoevenJohn Henry HoevenTrump’s economic policies spur GOP angst Crop sale incentive program is wrong policy for trade and security Sen. Steve Daines knows the ski slopes, residents MORE in North Dakota, former Sen. Dan CoatsDaniel (Dan) Ray CoatsPutin can learn from Gorbachev on how to gain from future US talks GOP senator blocking Trump's Intel nominee NSA nominee sails through second confirmation hearing MORE in Indiana and Rep. John BoozmanJohn Nichols BoozmanSpending talks face new pressure Bill to bolster gun background checks gains enough support to break filibuster Senate Republicans call on Trump to preserve NAFTA MORE in Arkansas -- all three Republican pickup opportunities.

The NRSC official also predicted Rep. Mark KirkMark Steven KirkHigh stakes as Trump heads to Hill Five things to watch for at Trump-Senate GOP meeting Giffords, Scalise highlight party differences on guns MORE and Pat Toomey "will in" in Illinios and Pennsylvania (respectively), and that Ken Buck is "poised to win" in Colorado.

In other races, Jesmer was more muted in his confidence. He wrote that the NRSC would provide Republican Ron JohnsonRonald (Ron) Harold JohnsonOvernight Health Care: House passes .3T omnibus | Bill boosts funds for NIH, opioid treatment | Senators spar over ObamaCare fix | 'Right to Try' bill heads to the Senate GOP pushes to change Senate rules for Trump House passes 'right to try' drug bill MORE with "whatever help he needs to maintain his lead" over Sen. Russ Feingold in Wisconsin.

Jesmer wouldn't make any predictions about the fate of Republican candidates John Raese in West Virginia, Sharron Angle in Nevada, Linda McMahon in Connecticut, Carly Fiorina in California, Dino Rossi in Washington state, or Christine O'Donnell in Delaware.

If Republicans were to pick up six seats in this election, it would likely be interpreted as a healthy victory for the party, but might also be seen as disappointing given prospects for even greater gains. It would be well short of the 10 seats Republicans need to gain in the Senate in order to win back a majority in the upper chamber -- assuming they hold onto all the seats currently held be Republicans.

Jesmer said that cash advantages for GOP party committees and candidates, combined with a political environment that favors Republicans, would enable victories for the party come Nov. 2.

"Given the hard facts, the onus is on Democrats to explain why – and how – their candidates can win with just 29 days until the election," he wrote.

Updated 1:07 p.m.