diff --git a/.github/sync-repo-settings.yaml b/.github/sync-repo-settings.yaml
index 4a30a08..1350fae 100644
--- a/.github/sync-repo-settings.yaml
+++ b/.github/sync-repo-settings.yaml
@@ -9,9 +9,9 @@ branchProtectionRules:
       - "ci/kokoro: System test"
       - docs
       - lint
-      - test (12)
       - test (14)
       - test (16)
+      - test (18)
       - cla/google
       - windows
       - OwlBot Post Processor
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index bd813c7..711957b 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [12, 14, 16, 18]
+        node: [14, 16, 18, 20]
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
diff --git a/.kokoro/continuous/node12/common.cfg b/.kokoro/continuous/node12/common.cfg
deleted file mode 100644
index ca0d61f..0000000
--- a/.kokoro/continuous/node12/common.cfg
+++ /dev/null
@@ -1,24 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
-
-# Build logs will be here
-action {
-  define_artifacts {
-    regex: "**/*sponge_log.xml"
-  }
-}
-
-# Download trampoline resources.
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
-
-# Use the trampoline script to run in docker.
-build_file: "node-gtoken/.kokoro/trampoline_v2.sh"
-
-# Configure the docker image for kokoro-trampoline.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/node:12-user"
-}
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/node-gtoken/.kokoro/test.sh"
-}
diff --git a/.kokoro/continuous/node12/lint.cfg b/.kokoro/continuous/node12/lint.cfg
deleted file mode 100644
index 220351b..0000000
--- a/.kokoro/continuous/node12/lint.cfg
+++ /dev/null
@@ -1,4 +0,0 @@
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/node-gtoken/.kokoro/lint.sh"
-}
diff --git a/.kokoro/continuous/node12/samples-test.cfg b/.kokoro/continuous/node12/samples-test.cfg
deleted file mode 100644
index 5a33015..0000000
--- a/.kokoro/continuous/node12/samples-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/node-gtoken/.kokoro/samples-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/continuous/node12/system-test.cfg b/.kokoro/continuous/node12/system-test.cfg
deleted file mode 100644
index 2281eed..0000000
--- a/.kokoro/continuous/node12/system-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/node-gtoken/.kokoro/system-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/continuous/node12/test.cfg b/.kokoro/continuous/node12/test.cfg
deleted file mode 100644
index e69de29..0000000
diff --git a/.kokoro/presubmit/node12/common.cfg b/.kokoro/presubmit/node12/common.cfg
deleted file mode 100644
index ca0d61f..0000000
--- a/.kokoro/presubmit/node12/common.cfg
+++ /dev/null
@@ -1,24 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
-
-# Build logs will be here
-action {
-  define_artifacts {
-    regex: "**/*sponge_log.xml"
-  }
-}
-
-# Download trampoline resources.
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
-
-# Use the trampoline script to run in docker.
-build_file: "node-gtoken/.kokoro/trampoline_v2.sh"
-
-# Configure the docker image for kokoro-trampoline.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/node:12-user"
-}
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/node-gtoken/.kokoro/test.sh"
-}
diff --git a/.kokoro/presubmit/node12/samples-test.cfg b/.kokoro/presubmit/node12/samples-test.cfg
deleted file mode 100644
index 5a33015..0000000
--- a/.kokoro/presubmit/node12/samples-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/node-gtoken/.kokoro/samples-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/presubmit/node12/system-test.cfg b/.kokoro/presubmit/node12/system-test.cfg
deleted file mode 100644
index 2281eed..0000000
--- a/.kokoro/presubmit/node12/system-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/node-gtoken/.kokoro/system-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/presubmit/node12/test.cfg b/.kokoro/presubmit/node12/test.cfg
deleted file mode 100644
index e69de29..0000000
diff --git a/package.json b/package.json
index 5e90724..f51f89d 100644
--- a/package.json
+++ b/package.json
@@ -5,7 +5,7 @@
   "main": "./build/src/index.js",
   "types": "./build/src/index.d.ts",
   "engines": {
-    "node": ">=12.0.0"
+    "node": ">=14.0.0"
   },
   "repository": "google/node-gtoken",
   "scripts": {
@@ -49,11 +49,11 @@
     "@types/mocha": "^9.0.0",
     "@types/node": "^18.0.0",
     "c8": "^8.0.0",
-    "gts": "^3.0.0",
+    "gts": "^3.1.1",
     "linkinator": "^4.0.0",
     "mocha": "^9.2.2",
     "nock": "^13.0.0",
-    "typescript": "^4.6.4"
+    "typescript": "^5.1.6"
   },
   "files": [
     "build/src",