(CNN) New Jersey Republican Rep. Rodney Frelinghuysen, the chairman of the powerful House Appropriations Committee, announced Monday he will not seek re-election in 2018.

Frelinghuysen's announcement comes as about three dozen other Republican members and a host of other House chairmen have announced their retirements or plans to run for other offices outside of Congress amid speculation that the 2018 midterms could be a wave election for Democrats.

"Today as I announce my retirement at the end of this session of Congress, I want to use the opportunity to strongly encourage the many young people I meet to consider public service," Frelinghuysen said in his statement.

The New Jersey congressman faced a tough re-election bid in 2018 and Republicans had long been worried that Frelinghuysen would retire. But as recently as last week, GOP aides had become more optimistic that he would seek re-election, saying they'd grown less troubled by his fundraising and his staff had become more engaged ahead of a tough re-election battle.

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